Equity trends in ownership of insecticide-treated nets in 19 sub-Saharan African countries

Bull World Health Organ 2017;95:322–332 | doi: http://dx.doi.org/10.2471/BLT.16.172924 Research 322 Equity trends in ownership of insecticide-treated nets in 19 sub- Saharan African countries Cameron Taylor,a Lia Floreya & Yazoume Yeb Introduction Equity in health is a major tenet of global development or- ganizations, such as the World Health Organization (WHO) and the World Bank, whose policies are aimed to decrease the gap between poor and rich populations. WHO defines health inequity as “inequality with respect to health determinants, access to the resources needed to improve and maintain health or health outcomes”.1 Many diseases, such as malaria, are not distributed equitably among populations. Malaria dispropor- tionately affects poor, rural populations, with pregnant women and young children at highest risk of severe morbidity and mortality.2–10 Addressing inequities that are actionable, such as the availability of commodities, has been the cornerstone of malaria control efforts for more than a decade. In April 2008 the Roll Back Malaria Partnership, together with the Secretary-General of the United Nations, launched the initiative Cover The Bed Net Gap to achieve the goal of universal bed-net coverage by December 2010.11,12 The aim of this initiative is to have every household at risk of malaria transmission and every person within that household pro- tected by an insecticide-treated net (ITN).13,14 Since the launch of the initiative, countries have achieved high ITN coverage levels using various distribution channels such as community delivery, routine health services or outreach activities. Before the launch of the initiative, many distribution strat- egies focused on populations at higher risk of malaria. The ITN policies frequently included distribution of nets to caregivers of children younger than five years during routine vaccination campaigns, distribution to pregnant women during antenatal care visits and via social marketing. In addition, ITNs could be purchased either at health facilities or in the private market. These distribution strategies led to inequity in ITN ownership among subgroups,2,15 particularly between socioeconomic subgroups. Richer households were more likely to own ITNs than the poorest households, probably as a result of low access to health care among the poorest populations.2,16,17 With the launch of the initiative, the distribution of ITNs shifted from targeted distribution to mass distribution campaigns. This shift gave malaria control programmes the opportunity to reduce disparities among subgroups by increasing ITN ownership18–24 to reduce the malaria burden.25 The mass distribution campaigns aim to provide one ITN for every two household members. Based on the longevity of the nets and the cost–effectiveness of conducting a mass distribution as compared to a targeted net replacement, these campaigns are recommended to take place every three years.26 In 2015, seven years after the launch of the initiative, few multicountry studies have documented the effect of the mass distribution strategy on equity in ITN ownership coverage in sub-Saharan Africa. This study assesses the level of equity in bed-net ownership before and after the widespread implemen- tation of national ITN distribution strategies. Methods Data We used data from Demographic and Health Surveys (DHS) and Malaria Indicator Surveys (MIS), which are nationally representative, population-based household surveys and which use validated standard methods in all countries. Further details can be found elsewhere.27 The analysis focused on malaria- endemic countries in sub-Saharan Africa that have conducted DHS or MIS between 2003 and 2014. We defined surveys made before the launch of the initiative as baseline surveys Objective To examine the change in equity of insecticide-treated net (ITN) ownership among 19 malaria-endemic countries in sub-Saharan Africa before and after the launch of the Cover The Bed Net Gap initiative. Methods To assess change in equity in ownership of at least one ITN by households from different wealth quintiles, we used data from Demographic and Health Surveys and Malaria Indicator Surveys. We assigned surveys conducted before the launch (2003–2008) as baseline surveys and surveys conducted between 2009–2014 as endpoint surveys. We did country-level and pooled multicountry analyses. Pooled analyses based on malaria transmission risk, were done by dividing geographical zones into either low- and intermediate-risk or high-risk. To assess changes in equity, we calculated the Lorenz concentration curve and concentration index (C-index). Findings Out of the 19 countries we assessed, 13 countries showed improved equity between baseline and endpoint surveys and two countries showed no changes. Four countries displayed worsened equity, two favouring the poorer households and two favouring the richer. The multicountry pooled analysis showed an improvement in equity (baseline survey C-index: 0.11; 95% confidence interval, CI: 0.10 to 0.11; and endpoint survey C-index: 0.00; 95% CI: −0.01 to 0.00). Similar trends were seen in both low- and intermediate-risk and high-risk zones. Conclusion The mass ITN distribution campaigns to increase coverage, linked to the launch of the Cover The Bed Net Gap initiative, have led to improvement in coverage of ITN ownership across sub-Saharan Africa with significant reduction in inequity among wealth quintiles. a The DHS Program, ICF, 530 Gaither Road, Suite 500, Rockville, MD 20850, United States of America (USA). b MEASURE Evaluation, ICF, Rockville, USA. Correspondence to Cameron Taylor (email: cameron.taylor@icf.com). (Submitted: 4 March 2016 – Revised version received: 6 January 2017 – Accepted: 13 January 2017 – Published online: 2 February 2017 ) R search Bull World Health Organ 2017;95:322–332| doi: http://dx.doi.org/10.2471/BLT.16.172924 323 Research Ownership of insecticide-treated nets in sub-Saharan AfricaCameron Taylor et al. and these were conducted between the years 2003–2008. Surveys carried out between years 2009–2014, we defined as endpoint surveys. All surveys are independent from each other. Analysis We did two sets of analyses: a country-lev- el equity trend analysis of ITN ownership and a multicountry pooled analysis exam- ining equity of ITN ownership by malaria transmission risk zones. Inclusion criteria for the country-level equity trend analyses included: (i) countries with one survey conducted between years 2003–2008 (baseline) and the other survey conducted between years 2009–2014 (endpoint); and (ii) all surveys must have included data on ITN ownership via a bed-net roster in the household questionnaire. To explore if equity in ITN owner- ship varies by level of malaria transmis- sion, the multicountry pooled equity analysis categorized all survey clusters into categories of malaria risk. We in- cluded surveys that had publicly available global positioning system (GPS) data for the surveyed clusters. If a country had more than one survey with GPS data in a time period, we used the most recent survey in both the baseline and endpoint. However, in Rwanda, we used the 2010 DHS GPS coordinates for the endpoint due to a lack of GPS coordinates for the most recent 2013 MIS survey. Only coun- tries with GPS data from both surveys were included in the pooled analysis. Defining ITN ownership The outcome of interest is household ITN ownership, defined as the proportion of households with at least one ITN. As recommended by the Roll Back Malaria Monitoring and Evaluation Reference Group, the indicator is standard across countries and reflects the extent to which ITN distribution campaigns have reached all households.28 For each survey, we calculated the proportion of households with at least one ITN. To test for signifi- cant changes in ITN ownership between baseline and endpoint surveys, we cal- culated 95% confidence intervals (CI). We did not use the indicator for universal bed-net coverage, i.e. the proportion of households with at least one ITN for every two people, since the indicator was not launched until 2008 and therefore not captured in baseline surveys. Defining wealth quintiles The DHS wealth index measures eco- nomic well-being of households in- dependently from health and educa- tion.29,30 The DHS wealth index is a survey-specific measure of the relative economic status of households based on analysis of household assets and service amenities at a particular point in time. Wealth quintiles (lowest, second, middle, fourth, and highest) ranking indicates relative rather than absolute economic status of the household.30–32 Defining malaria endemicity We assigned each household cluster into geographical zones based on malaria transmission risk. To link DHS and MIS geo-coordinates (latitude, longitude) of each survey cluster to transmission risk zones, we used geo-coordinated Plas- modium falciparum parasite prevalence rates among children aged 2–10 years (PfPR2–10) from the Malaria Atlas Project 2010.33 We assigned all households in a cluster from the DHS or MIS survey Table 1. Countries included in country-level and pooled equity analysis for insecticide-treated net ownership, sub-Saharan Africa, 2003–2014 Country Baseline survey, type and year Mid-point survey, type and year Endpoint survey, type and year PfPR2–10, a % Included in pooled analysisb Angola 2006–2007 MIS N/A 2011 MIS 8.1 Yes Benin 2006 DHS N/A 2011–12 DHS 29.9 No Burkina Faso 2003 DHS N/A 2010 DHS 65.4 Yes Cameroon 2004 DHS N/A 2011 DHS/MICS 23.5 Yes Congo 2005 DHS N/A 2011–2012 DHS 17.5 No Democratic Republic of the Congo 2007 DHS N/A 2013–2014 DHS 48.0 Yes Guinea 2005 DHS N/A 2012 DHS/MICS 42.4 Yes Madagascar 2008–2009 DHS 2011 MIS 2013 MIS 5.8 Yes Malawi 2004 DHS 2010 DHS 2012 MIS 35.6 Yes Mali 2006 DHS N/A 2012–2013 DHS 32.0 Yes Mozambique 2007 MIS N/A 2011 DHS 35.5 No Niger 2006 DHS N/A 2012 DHS 29.3 No Nigeria 2008 DHS 2010 MIS 2013 DHS 32.5 Yes Rwanda 2005 DHS 2010 DHS 2013 MIS 2.3 Yes Senegal 2005 DHS 2008–2009 MIS 2010–2011 DHS 5.8 Yes Sierra Leone 2008 DHS N/A 2013 DHS 52.8 Yes Uganda 2006 DHS 2009 MIS 2011 DHS 37.0 Yes United Republic of Tanzania 2004–2005 DHS 2007–2008 THMIS 2011–2012 THMIS 10.6 Yes Zimbabwe 2005–2006 DHS N/A 2010–2011 DHS 2.5 Yes DHS: Demographic Health Survey; MICS: Multiple Indicator Cluster Surveys; MIS: Malaria Indicator Survey; N/A: not available; PfPR2–10: Plasmodium falciparum parasite rate; THMIS: Tanzania human immunodeficiency virus and malaria indicator survey. a PfPR2–10 is the national mean of Plasmodium falciparum parasite rate in children aged 2–10 years and was obtained from the 2010 Malaria Atlas Project. 33 b Countries with no GPS data for both surveys were excluded from the pooled-analysis. Bull World Health Organ 2017;95:322–332| doi: http://dx.doi.org/10.2471/BLT.16.172924324 Research Ownership of insecticide-treated nets in sub-Saharan Africa Cameron Taylor et al. data to the same malaria transmission risk zone based on corresponding PfPR2–10 data for that cluster.34 For the transmission zone categories, we used the standard PfPR2–10 cut-offs from the Malaria Atlas Project: no-risk: PfPR2–10 < 0.1%; low-risk: 0.1% > PfPR2–10 ≤ 5%; intermediate-risk: 5% > PfPR2–10 ≤ 40%; and high-risk: PfPR2–10 > 40%.35 Out of the 346 272 household clusters located in 15 countries, 50% (173 136) were categorized in the high- risk category, 36% (124 658) in the intermediate-risk category, 10% (34 627) in the low-risk category and 4% (13 851) in the no-risk category. We excluded clusters located in areas with no risk of malaria from analyses because popula- tions in these areas would not be tar- geted by ITN distribution campaigns. Due to small sample size in the low-risk group, we combined the intermediate and the low-risk groups. Equity calculation We used the Lorenz concentration curve (C-curve) and the Lorenz concentra- tion index (C-index) to assess equity in household ITN ownership across household wealth quintiles. The C- curve graphically presents the degree of economic-related inequality.36,37 In the C-curve graphs, the x-axis presents the cumulative percentage of the sample, ranked by wealth, beginning with the poorest, while the y-axis presents the cumulative percentage of the variable of interest corresponding to the cu- mulative percentage of the distribution of wealth.36 In the C-curve graphs, the dashed 45° line represents equity where- by the health outcome is distributed equally among all wealth quintiles. The C-curve will be below the equity line if ITN ownership is concentrated in richer households and will be above the equity line if ITN ownership is predominantly among poorer households. The C-index, which provides quan- tification of this measure of equity, is defined as twice the area between the C-curve and the 45° line of equity. We calculated the C-index values by using the following equation C = (P1L2− P2L1)+(P2L3−P3L2)+…+(Pt-1Lt−PtLt-1), where P is the cumulative percentage of the household ranked by economic sta- tus in group t, and L is the corresponding concentration curve ordinate.37 C-index values range between −1 to 1. A value of Fig. 1. Proportion of households with at least one insecticide-treated net by country and survey year, 19 countries in sub-Saharan Africa, 2003–2014 Pr op or tio n of h ou se ho ld s w ith at le as t o ne IT N (% ) 100 80 60 40 20 0 100 80 60 40 20 0 100 80 60 40 20 0 100 80 60 40 20 0 100 80 60 40 20 0 100 80 60 40 20 0 100 80 60 40 20 0 100 80 60 40 20 0 100 80 60 40 20 0 100 80 60 40 20 0 100 80 60 40 20 0 100 80 60 40 20 0 100 80 60 40 20 0 100 80 60 40 20 0 100 80 60 40 20 0 100 80 60 40 20 0 100 80 60 40 20 0 100 80 60 40 20 0 100 80 60 40 20 0 Year Year Year Year Year Year Year Year Year Year Year Year Year Year Year Year Year Year Year 2006–2007 2011 2006 2011–2012 2007 2013–2014 2005 2011–2012 2006 2012–20132008–20092011 2013 2003 2010 2005 2012 2007 2011 2008 2013 2006 2012 2004 2011 2004 2010 2012 2008 2010 2013 2006 2009 2011 2005 2010 2013 2005–2006 2010–2011 2005 2008– 2009 2010– 2011 2004– 2005 2007– 2008 2011– 2012 Baseline survey Midpoint survey Endpoint survey 95% CI 28 16 9 37 25 43 4 16 47 6 8 28 23 39 2 15 82 27 9 8 20 60 50 35 51 70 64 80 61 47 60 57 5042 69 80 5757 91 36 83 55 29 33 63 84 Angola Mozambique Democratic Republic of the Congo Sierra Leone Benin Niger Guinea Uganda Burkina Faso Nigeria Madagascar United Republic of Tanzania Cameroon Rwanda Malawi Zimbabwe Congo Senegal Mali CI: confidence interval; ITN: insecticide-treated net. Bull World Health Organ 2017;95:322–332| doi: http://dx.doi.org/10.2471/BLT.16.172924 325 Research Ownership of insecticide-treated nets in sub-Saharan AfricaCameron Taylor et al. 0 suggests no difference in ITN owner- ship between different wealth quintiles. A C-index larger than 0 suggests that ITN ownership is predominantly among the richer households. Conversely, a negative index indicates that ITN own- ership is more concentrated among the poorer households.17,38 We used the concindc command in Stata version 13 (StataCorp. LP, College Station, United States of America) to calculate the C-index values and their standard errors and we used the clorenz command for producing the C-curves. We calculated 95% CI for the C-index values. Results In total, 19 countries (45 surveys) met the inclusion criteria for country-level equity analysis. For the multicountry pooled equity analysis, we included 15 countries (30 surveys; Table 1). ITN ownership In all countries, except Angola, there was a statistically significant increase in ITN ownership between the baseline and endpoint surveys. Rwanda and the United Republic of Tanzania showed the greatest improvement in ITN ownership, from 15% to 83% and from 23% to 91%, respectively. Angola displayed the small- est improvements in ITN ownership (from 28% to 35%; Fig. 1). Country-level equity analysis At the country level, 13 out of the 19 countries showed improvements in equity of ITN ownership between base- line and endpoint surveys, while two countries showed no changes and four countries displayed worsened equity (Table 2). For all countries showing improve- ments in equity, the ITN ownership was concentrated in households from the highest wealth quintiles in the baseline surveys, as indicated by a C-curve below the equity line (C-index > 0). However, the countries showed different levels of improvement. For Burkina Faso, the Democratic Republic of the Congo, Malawi, Rwanda and Uganda equity significantly improved with C-index values closer to zero in the endpoint surveys. For Benin, Cameroon and the United Republic of Tanzania, equity in ITN ownership across wealth quintiles (C-index = 0) had been achieved. The endpoint surveys from the Congo, Guin- ea, Nigeria, Sierra Leone and Zimbabwe showed higher levels of ITN ownership among poorer households (C-curve above the equity line and C-index < 0; Fig. 2; Table 2). In Mali, ITN ownership was equally distributed across wealth quintiles in both baseline and endpoint surveys with no significant change. In Mozambique, ITN ownership remained concentrated among richer households in the end- point survey. However, C-index values were close to zero (Fig. 2; Table 2). Table 2. Equity changes in ownership of insecticide-treated nets before and after the launch of the Cover The Bed Net Gap initiative, sub-Saharan Africa, 2003–2014 Equity change Country C-index (95% CI) Baseline survey Endpoint survey Improved From ownership concentrated in richer households to more equitable ownership, but still concentrated in richer households Burkina Faso 0.45 (0.40 to 0.49) 0.06 (0.05 to 0.06) Democratic Republic of the Congo 0.26 (0.23 to 0.30) 0.03 (0.03 to 0.04) Malawi 0.29 (0.28 to 0.31) 0.06 (0.04 to 0.07) Rwanda 0.35 (0.33 to 0.38) 0.02 (0.02 to 0.03) Uganda 0.11 (0.09 to 0.14) 0.02 (0.02 to 0.03) From ownership concentrated in richer households to equitable ownership Benin 0.23 (0.21 to 0.24) 0.00 (−0.01 to 0.00) Cameroon 0.25 (0.17 to 0.33) 0.02 (0.00 to 0.03) United Republic of Tanzania 0.41 (0.39 to 0.43) −0.01 (−0.01 to 0.00) From ownership concentrated in richer households to more equitable ownership but concentrated in poorer households Congo 0.15 (0.10 to 0.20) −0.11 (−0.12 to −0.09) Guinea 0.28 (0.21 to 0.35) −0.03 (−0.04 to −0.02) Nigeria 0.18 (0.16 to 0.20) −0.06 (−0.06 to −0.05) Sierra Leone 0.05 (0.04 to 0.07) −0.02 (−0.03 to −0.01) Zimbabwe 0.19 (0.15 to 0.22) −0.06 (−0.08 to −0.04) No change Ownership equitably distributed in both surveys Mali 0.02 (0.00 to 0.03) 0.00 (0.00 to 0.01) Ownership was concentrated in richer households in both surveys Mozambique 0.05 (0.02 to 0.08) 0.04 (0.03 to 0.05) Worsened Favouring poorer households From ownership concentrated in poorer households to increased ownership concentrated in poorer households Madagascar −0.04 (−0.04 to −0.03) −0.06 (−0.07 to −0.05) Senegal −0.01 (−0.05 to 0.00) −0.11 (−0.12 to −0.10) Favouring richer households From equitable ownership or ownership concentrated in richer households to concentrated ownership in richer households Angola 0.05 (0.01 to 0.08) 0.17 (0.15 to 0.18) Niger 0.00 (−0.02 to 0.01) 0.09 (0.08 to 0.10) CI: confidence interval; C-index: concentration index; ITN: insecticide-treated net. Notes: Cover The Bed Net Gap was an initiative launched by the Roll Back Malaria Partnership in April 2008.12 Years of the surveys are given in Table 1. A value of 0 suggests no difference in ITN ownership between different wealth quintiles. A C-index larger than 0 suggests that ITN ownership is concentrated among the richer households. Conversely, a negative index indicates that ITN ownership is more concentrated among the poorer households.17,38 Bull World Health Organ 2017;95:322–332| doi: http://dx.doi.org/10.2471/BLT.16.172924326 Research Ownership of insecticide-treated nets in sub-Saharan Africa Cameron Taylor et al. Madagascar and Senegal maintained levels of inequity that favoured the poorest households. In Angola and Niger, while the inequity in the baseline surveys was close to zero, in the endpoint surveys, household ITN ownership increased and was in favour of the richer households (Fig. 2; Table 2). Fig. 3 shows a scatter plot of the C- index by ITN ownership for all surveys included in the country-level analyses. The plot indicates a decline in the dis- parity of the C-index values as ITN cov- erage increases. Surveys that took place between 2009–2014 have higher levels of ITN ownership and greater equity compared to surveys from 2003–2008. Pooled equity analysis All countries The multicountry pooled analysis indi- cates a significant improvement in ITN ownership equity between baseline (C- index: 0.11; 95% CI: 0.10 to 0.11) and endpoint surveys (C-index: 0.00; 95% CI: −0.01 to 0.00; Fig. 4) By transmission risk In high malaria transmission risk zones, ITN ownership was concen- trated in households from the higher wealth quintiles in the baseline surveys (C-index: 0.07; 95% CI: 0.06 to 0.08). However, in the endpoint surveys this inequity was no longer evident (C-index: 0.00; 95% CI: 0.00 to 0.01; Fig. 4). In the Fig. 2. Equity changes in insecticide-treated net ownership by country, 19 countries in sub-Saharan Africa, 2003–2014 Cumulative percentage of wealth quintiles Cumulative percentage of wealth quintiles Cumulative percentage of wealth quintiles Cumulative percentage of wealth quintiles Cumulative percentage of wealth quintiles Cumulative percentage of wealth quintiles Cumulative percentage of wealth quintiles Cumulative percentage of wealth quintiles Cumulative percentage of wealth quintiles Cumulative percentage of wealth quintiles Cumulative percentage of wealth quintiles Cumulative percentage of wealth quintiles Equity line Equity line Equity line Equity line Equity line Equity line Equity line Equity line Equity line Equity line Equity line Equity line 2006–2007 survey 2005 survey 2004 survey 2006 survey 2007 survey 2006 survey 2006 survey 2005 survey 2007 survey 2011 survey 2006 survey 2013 survey 2012 survey 2004 survey 2011 survey 2011–2012 survey 2010 survey 2012 survey 2011–2012 survey 2013–2014 survey 2012–2013 survey 2008–2009 survey 2010 survey 2012 survey 2011 survey 2011 survey Cu m ul at iv e % o f w ea lth q ui nt ile s a m on g ho us eh ol ds ow ni ng at le as t o ne IT N 100 80 60 40 20 0 100 80 60 40 20 0 100 80 60 40 20 0 100 80 60 40 20 0 100 80 60 40 20 0 100 80 60 40 20 0 100 80 60 40 20 0 100 80 60 40 20 0 100 80 60 40 20 0 100 80 60 40 20 0 100 80 60 40 20 0 100 80 60 40 20 0 20 40 60 80 100 20 40 60 80 100 20 40 60 80 100 20 40 60 80 100 20 40 60 80 100 20 40 60 80 100 20 40 60 80 100 20 40 60 80 100 20 40 60 80 100 20 40 60 80 100 20 40 60 80 100 20 40 60 80 100 Angola Congo Malawi Benin Democratic Republic of the Congo Mali Burkina Faso Guinea Mozambique Cameroon Madagascar Niger continues ... Bull World Health Organ 2017;95:322–332| doi: http://dx.doi.org/10.2471/BLT.16.172924 327 Research Ownership of insecticide-treated nets in sub-Saharan AfricaCameron Taylor et al. low and intermediate malaria transmis- sion risk zones, the ITN ownership was in favour of richer households in the baseline surveys (C-index: 0.14; 95% CI: 0.13 to 0.14), but shifted to favour the poorer households in the endpoint surveys (C-index: −0.01, 95% CI: −0.02 to −0.01; Fig. 4). Discussion This study presents evidence of the positive impact of mass ITN distribution strategies on equity of ITN ownership in 19 malaria-endemic countries in sub- Saharan Africa. In 15 of the 19 countries analysed, ITN ownership either became more equitable or maintained equity between baseline and endpoint surveys. In four countries, improvements in equity could not be detected between the two surveys: in two countries the ITN ownership remained concentrated among households from the lowest wealth quintiles, while in the other two, ITN ownership remained concentrated among the richer households. The pooled multicountry analyses further supported the findings that the significant increase in ITN ownership has favoured the poorest households in most settings. In the countries where ITN ownership either became more equitable or maintained equity, all showed a significant increase in the proportion of households with at least one ITN between baseline and endpoint surveys. In countries with very high levels of household ITN ownership, such as Rwanda and the United Republic of Tanzania, the chances of equitable dis- tribution are inherently higher. Thus, the recent funding for malaria control25 and the subsequent investment in mass ITN distribution campaigns have likely contributed to reduced inequity among wealth quintiles by increasing overall coverage. Angola, Mali, Mozambique and Niger had close to equitable ITN own- ership in their baseline surveys despite relatively low overall levels of ITN own- ership. This finding could be due to early implementation of focused nationwide campaigns where ITN distributions were integrated with child health cam- paigns.19,40–42 In Mali and Mozambique, ITN ownership remained equitably distributed in endpoint surveys, possibly due to the rollout of net-distribution campaigns to achieve universal coverage in 2008 and 2011.43,44 However, Angola and Niger experienced a decrease in equity in their endpoint surveys despite low inequity at baseline. The trend of increasing inequity in Angola could be partially due to the timing of campaigns in relationship to the survey as well as a shift in ITN distribution from integrated campaigns to distribution in only se- lected municipalities.45 Reasons for the worsened equity in Niger is less clear, but ITN: insecticide-treated net. Note: A survey line under the equity line denotes that ITN ownership was more concentrated in richer households, while a survey line above the equity line represents ownership favouring the poorer households. ... continued Cumulative percentage of wealth quintiles Cumulative percentage of wealth quintiles Cumulative percentage of wealth quintiles Cumulative percentage of wealth quintiles Cumulative percentage of wealth quintiles Cumulative percentage of wealth quintiles Cumulative percentage of wealth quintiles Equity line Equity line Equity line Equity line Equity line Equity line Equity line2008 survey 2006 survey 2005 survey 2005 survey 2008 survey 2013 survey2010 survey 2009 survey 2013 survey 2011 survey 2010–2011 survey 2007–2008 survey 2011–2012 survey 2008–2009 survey 2004–2005 survey 2005–2006 survey 2010–2011 survey 2010–2011 survey 2013 survey Cu m ul at iv e % o f w ea lth q ui nt ile s a m on g ho us eh ol ds ow ni ng at le as t o ne IT N 100 80 60 40 20 0 100 80 60 40 20 0 100 80 60 40 20 0 100 80 60 40 20 0 100 80 60 40 20 0 100 80 60 40 20 0 100 80 60 40 20 020 40 60 80 100 20 40 60 80 100 20 40 60 80 100 20 40 60 80 100 20 40 60 80 100 20 40 60 80 100 20 40 60 80 100 Nigeria Uganda Rwanda United Republic of Tanzania Senegal Zimbabwe Sierra Leone Bull World Health Organ 2017;95:322–332| doi: http://dx.doi.org/10.2471/BLT.16.172924328 Research Ownership of insecticide-treated nets in sub-Saharan Africa Cameron Taylor et al. possible explanations could include the lack of implementation of free ITN dis- tribution campaigns between baseline and endpoint surveys.19,25 Madagascar and Senegal were the only countries that maintained levels of inequity from base- line to endpoint in favour of households from the lowest wealth quintiles. The trend seen in Congo, Guinea, Nigeria, Sierra Leone and Zimbabwe – i.e. ITN ownership shifted from being concentrated in the richer households to being concentrated in the poorer households – is not surprising. These countries have moved towards universal ITN coverage for populations at-risk and shifted their distribution of ITNs to high-risk rural-areas, which are usu- ally less wealthy than urban centres.2 Another reason for this trend may be that wealthier households have access to a wider range of other effective interven- tions, such as improved housing with screened windows and doors and closed eaves that make ITNs less essential for malaria prevention. To explore if equity of ITN own- ership varies by malaria transmission risk, we pooled clusters into two groups stratified by low/intermediate and high levels of malaria transmission. In the pooled analysis, equity increased sig- nificantly in both groups. However, the greatest improvement in equity occurred in clusters in low- and intermediate-risk zones. The observed results could be due to changing ITN policies between baseline and endpoint surveys, and more specifically, the rollout of free mass dis- tribution campaigns after 2008. Before 2008, financial and logistic constraints caused most distribution campaigns to be targeted to high-risk populations (children younger than five years and pregnant women) and/or high-risk re- gions (rural, high-transmission zones). Therefore, households from the lowest wealth quintiles in low- and intermedi- ate-risk zones were less likely to own a net if they did not have access to health- care services or could not afford to pay for a net at market price. The shift to free mass distribution campaigns may have improved equity by providing access to the households from the lowest wealth quintiles that did not have previous ac- cess to nets. This study has a few limitations that should be highlighted. The wealth quintiles are based on assets, which may be different from country to country as the individual assets might have differ- ent weights in the principal component analysis. While the analysis used data from 19 countries, other countries may have experienced changes in equity, but were not captured in this analysis. In ad- dition, we excluded four of the countries Fig. 4. Equity changes in insecticide-treated net ownership by malaria transmission risk zone, 15 countries in sub-Saharan Africa, 2003–2014 Cumulative % of wealth quintiles Cumulative % of wealth quintiles Cumulative % of wealth quintiles Equity line Equity line Equity line Baseline surveys (2003–2008) Baseline surveys (2003–2008) Baseline surveys (2003–2008) Endpoint surveys (2009–2014) Endpoint surveys (2009–2014) Endpoint surveys (2009–2014) 20 40 60 80 100 20 40 60 80 100 20 40 60 80 100 High malaria transmission risk zones Low and intermediate malaria transmission risk zones Cu m ul at ive % o f w ea lth q ui nt ile s a m on g ho us eh ol ds o w ni ng at le as t o ne IT N Cu m ul at ive % o f w ea lth q ui nt ile s a m on g ho us eh ol ds o w ni ng at le as t o ne IT N Cu m ul at ive % o f w ea lth q ui nt ile s a m on g ho us eh ol ds o w ni ng at le as t o ne IT N 100 80 60 40 20 0 100 80 60 40 20 0 100 80 60 40 20 0 All risk zones ITN: insecticide-treated net. Notes: Each household cluster was assigned a malaria transmission risk category based on Plasmodium falciparum parasite prevalence rates among children aged 2–10 years (PfPR2–10) from the Malaria Atlas Project 2010.33 We used the standard PfPR2–10 cut-offs from the Malaria Atlas Project: low and intermediate risk: 0.1% > PfPR2–10 < 40% and high risk: PfPR2–10 > 40%. A survey line under the equity line denotes that ITN ownership was more concentrated in richer households, while a survey line above the equity line represents ownership favouring the poorer households. Bull World Health Organ 2017;95:322–332| doi: http://dx.doi.org/10.2471/BLT.16.172924 329 Research Ownership of insecticide-treated nets in sub-Saharan AfricaCameron Taylor et al. used in the country-level analysis from the pooled analysis due to a lack of GPS data. This study focused on equity of ITN ownership and did not assess ITN use or ITN access, i.e. the proportion of the population who could use an ITN with the assumption that one ITN can protect two individuals. Future studies should examine equity of ITN access as it is a more comprehensive mea- sure of the level of protection within a household. With more countries imple- menting universal bed-net coverage strategies, capturing changes in equity of ITN access through survey data will be possible. In conclusion, our findings sup- port the hypothesis that national ITN distribution campaigns have increased ITN coverage and reduced economic inequity in ITN ownership since the launch of the Cover The Bed Net Gap initiative in 2008.12 However, further improvements are sti l l needed to reach and maintain coverage targets. With the combination of increased ITN distribution through multiple adapted distribution mechanisms and monitoring inequities to ensure that the poorest are also get protected, great strides can be made towards malaria prevention across sub-Saharan countries. ■ Acknowledgements Cameron Taylor and Lia Florey were supported through the DHS Program by the United States Agency for In- ternational Development (USAID) and the President’s Malaria Initia- tive (PMI) (#AIDOAA-C-13-00095). Yazoume Ye was supported through the MEASURE Evaluation Project by PMI through USAID under the terms of the MEASURE Evaluation cooperative agreement AID-OAA-L-14-00004. The MEASURE Evaluation is implemented by the Carolina Population Center at the University of North Carolina at Chapel Hill in partnership with ICF Interna- tional; John Snow, Inc.; Management Sciences for Health; Palladium; and Tulane University. Competing interests: None declared. Fig. 3. Proportion of households with at least one insecticide-treated net, by concentration index, sub-Saharan Africa, 2003–2014 C- in de x ( % ) 0.5 0.4 0.3 0.2 0.1 0.0 -0.1 -2.0 ITN universal coverage Equity line Proportion of households with at least one ITN Baseline surveys (2003–2008) Endpoint surveys (2009–2014) 0 20 40 60 80 100 C-index: concentration-index; ITN: insecticide-treated net. Note: We used the Lorenz C-index to assess equity in household ITN ownership across household wealth quintiles. ITN universal coverage of 80% is based on the Global Strategic Plan 2005–2015.39 صخلم ءارحصلا بيونج ةعقاو ةيقيرفأ ةلود 19 في يشرح ديبمب ةلجاعلما تايسومانلا كلاتما بسن في ةاواسلما تاهاتجا تايسومانلا كلاتما في ةاواسم ةبسن في يرغتلا صحف ضرغلا شرتنت يتلا لودلا نم ةلود 19 ينب )ITN( يشرح ديبمب ةلجاعُلما ةردابم قلاطنا لبق ةيقيرفلأا ءارحصلا بونجب ةعقاولا ايرلالما اهيف .اهقلاطنا دعبو “ةيسومانلاب ريسرلا ةيطغت” تلائاعلا كلاتما في ةاواسلما لىع ئراطلا يريغتلا مييقت ةقيرطلا ديبمب ةلجاعم ةدحاو ةيسومانل ةفلتمخ ةيناكس ةيسخم تائف نمض تاعلاطتسلاا نم ةدراولا تانايبلا انمدختساو ،لقلأا لىع يشرح ةقلعتلما حوسلماو ةيحصلا بناولجاو ةيناكسلا صئاصلخاب ةطبترلما 2003( قلاطنلاا لبق اهانيرجأ يتلا حوسلما دانسإب انمقو .ايرلالماب ينب ام ةترفلا في اهانيرجأ يتلا حوسلماو ةيساسأ حوسمك )2008 – لىع ليلاتح ءارجإب انمقو .ةياهنلا ةطقنل حوسمك 2014 – 2009 ليلاحتلا ءارجإ متو .نادلب ةدع ينب عمتج ىرخأو يرطقلا ىوتسلما قطانلما ميسقت ةطساوب ايرلالما راشتنا رطخ لىع ةدمتعلما ةعمالجا ىرخأ قطانمو ،ةطسوتمو ةضفخنم رطخ بسنب قطانم لىإ ةينكسلا انمق ،ةاواسلما لىع ةئراطلا تايرغتلا مييقتل .ةعفترم رطخ بسنب .)C-index( زيكترلا شرؤمو زنرول زيكرت ىنحنم باسحب اًنستح ةلود 13 ترهظأ ،مييقتلل تعضخ ةلود 19 نمض جئاتنلا رِهظُت لمو ،ةياهنلا ةطقنل حوسمو ةيساسلأا حوسلما ينب ةاواسلما في ،ةاواسلما نم ةئيدر ةجرد لود عبرأ ترهظأو .تايريغت يأ ناتلود سرُلأا ناتلود تلضف مايف رقفلأا سرُلأا ناتلود تلضف ثيح ةاواسلما في اًنستح نادلب ةدعل عمالجا ليلحتلا رهظأ ماك .ىنغلأا ةبسنل رادقمك 95% ؛0.11 :غلبي سياسلأا حسملل زيكرت شرؤم( :ةياهنلا ةطقن حسم زيكرت شرؤمو ،0.11 لىإ 0.10 :ةيحجرلأا ماك .)0.00 لىإ -0.01 :ةيحجرلأا ةبسنل رادقمك % 95 ؛0.00 ضفخنلما رطلخا ىوتسم تاذ قطانلما في ةبهاشتم تاهاتجا ترهظ .عفترلما رطلخا ىوتسمو طسوتلماو ةلجاعلما تايسومانلا كلاتما تلاملح لئالها راشتنلاا ىدأ جاتنتسلاا ريسرلا ةيطغت ةردابم قلاطنا عم – ةيطغتلا ةدايزل يشرح ديبمب ةلجاعلما ةيسومانلا كلاتما ةيطغت في نستح ثودح لىإ – ةكبشلاب عم ءارحصلا بونجب ةعقاولا ةيقيرفلأا لودلا برع يشرح ديبمب .ةيسملخا ةيناكسلا تائفلا ينب ةاواسلما مدع في ظوحلم ضافخنا Bull World Health Organ 2017;95:322–332| doi: http://dx.doi.org/10.2471/BLT.16.172924330 Research Ownership of insecticide-treated nets in sub-Saharan Africa Cameron Taylor et al. 摘要 19 个撒哈拉以南非洲国家拥有杀虫剂浸泡蚊帐的公平性趋势 目的 旨在调查 19 个撒哈拉以南非洲国家在推行消除 蚊帐差异举措前后拥有杀虫剂浸泡蚊帐 (ITN) 的公平 性变化。 方法 为了评估不同财富五分位家庭至少拥有一个杀虫 剂浸泡蚊帐 (ITN) 的公平性变化，我们使用了“人口 与健康调查”和“疟疾检测指标调查”中的数据。我 们将举措推行前（2003-2008 年）开展的调查指定为基 线调查，而将 2009-2014 年间的调查指定为端点调查。 我们开展了国家层面上的分析和多国家汇总分析。汇 总分析基于疟疾传播风险，通过将地理区域划分成中 低风险或高风险来展开。为了评估公平性变化，我们 计算了洛伦兹浓度曲线和浓度指标（C- 指标）。 结果 在我们评估的 19 个国家中，有 13 个国家在基 线和端点调查之间表现出公平性有所提高，两个国 家没有表现出任何变化。四个国家呈现出公平性降 低，其中两个国家有利于更贫穷的家庭，另两个国 家有利于更富裕的家庭。多国家汇总调查表现出公 平性有所提高（基线调查 C- 指标 ： 0.11 ；95% 置信区 间，CI ： 0.10 至 0.11 ；端点调查 C- 指标 ： 0.00; 95% CI: –0.01 至 0.00）。 中低风险和高风险区的趋势与之类 似。 结论 为提高覆盖率而进行的大规模杀虫剂浸泡蚊 帐 (ITN) 与消除蚊帐差异举措的推行相呼应，提高了 撒哈拉以南非洲国家杀虫剂浸泡蚊帐 (ITN) 的覆盖率， 并且显著降低了财富五分位家庭间的不公平性。 Résumé Tendances en matière d’égalité de possession de moustiquaires imprégnées d’insecticide dans 19 pays d’Afrique subsaharienne Objectif Examiner les changements au niveau de l’égalité de possession de moustiquaires imprégnées d’insecticide (MII) dans 19 pays d’Afrique subsaharienne où le paludisme est endémique, avant et après le lancement de l’initiative Cover the bed net gap. Méthodes Afin d’évaluer les changements concernant l’égalité de possession d’au moins une MII par ménage, dans différents quintiles de richesse, nous avons utilisé des données provenant des enquêtes démographiques et sanitaires ainsi que des enquêtes sur les indicateurs du paludisme. Les enquêtes menées avant le lancement de l’initiative (2003–2008) ont été prises comme enquêtes de référence et celles menées de 2009 à 2014 comme enquêtes finales. Nous avons effectué des analyses par pays ainsi que des analyses regroupées multi-pays. Les analyses regroupées en fonction du risque de transmission du paludisme ont été effectuées en divisant les zones géographiques selon que le risque était faible ou intermédiaire ou bien élevé. Pour évaluer les changements en matière d’égalité, nous avons calculé la courbe de concentration de Lorenz ainsi que l’indice de concentration (indice C). Résultats Sur les 19 pays que nous avons étudiés, 13 montraient une amélioration de l’égalité entre l’enquête de référence et l’enquête finale, et deux pays ne présentaient aucun changement. Quatre pays affichaient une moins bonne égalité: deux qui favorisaient les ménages les plus pauvres et deux les plus riches. L’analyse regroupée multi-pays a révélé une amélioration de l’égalité (indice C de l’enquête de référence: 0,11; intervalle de confiance (IC) de 95%: 0,10 à 0,11; indice C de l’enquête finale: 0,00; IC 95%: −0,01 à 0,00). Des tendances similaires ont été observées entre les zones à risque faible et intermédiaire et celles à risque élevé. Conclusion Les campagnes de distribution massive de MII visant à améliorer la couverture, associées au lancement de l’initiative Cover the bed net gap, ont permis d’augmenter le taux de possession de MII en Afrique subsaharienne et de réduire significativement les inégalités entre quintiles de richesse. Резюме Изменения в степени равномерности распределения обработанных инсектицидами противомоскитных сеток в 19 странах Африки к югу от Сахары Цель Изучить изменения в степени равномерности распределения обработанных инсектицидами противомоскитных сеток в 19 эндемичных по малярии странах Африки к югу от Сахары до и после запуска инициативы Преодоление неравенства в распределении надкроватных сеток. Методы Чтобы оценить изменение степени равномерности распределения по крайней мере одной обработанной инсектицидами противомоскитной сетки на семью из разных квинтилей доходов, авторы использовали данные демографических обследований и обследований состояния здоровья населения, а также данные обследований по показателям малярии. Обследования, проведенные до запуска инициативы (2003–2008 гг.), были определены как первоначальные обследования, а обследования, проведенные в 2009–2014 гг., — как заключительные. Были проведены анализы на уровне страны и объединенные анализы по нескольким странам. Объединенные анализы, основанные на риске заражения малярией, были проведены путем разделения географических зон на зоны с низким, средним и высоким уровнем риска. Для оценки изменения степени равномерности авторы рассчитали кривую концентрации Лоренца и показатель концентрации (C-индекс). Результаты Из 19 стран, подвергнутых оценке, в 13 наблюдалось увеличение степени равномерности в период между первоначальными и заключительными обследованиями, а в двух странах изменения отсутствовали. В четырех странах степень равномерности уменьшилась, причем в двух из них сетки были более распространены среди более бедных семей, а в двух других — среди более богатых. Согласно результатам объединенного анализа по нескольким странам, степень равномерности увеличилась (C-индекс при первоначальных обследованиях: 0,11; 95%-й доверительный интервал, ДИ: 0,10–0,11; C-индекс при заключительных обследованиях: 0,00; 95%-й ДИ: −0,01–0,00). Аналогичные тенденции наблюдались в зонах с низким, средним и высоким риском. Bull World Health Organ 2017;95:322–332| doi: http://dx.doi.org/10.2471/BLT.16.172924 331 Research Ownership of insecticide-treated nets in sub-Saharan AfricaCameron Taylor et al. Вывод Кампании по массовому распространению обработанных инсектицидами противомоскитных сеток, связанные с запуском инициативы Преодоление неравенства в распределении надкроватных сеток , привели к увеличению охвата обработанными инсектицидами противомоскитными сетками в разных странах Африки к югу от Сахары на фоне значительного сокращения неравенства среди квинтилей дохода. Resumen Tendencias de equidad en la propiedad de mosquiteros tratados con insecticida en 19 países del África subsahariana Objetivo Examinar el cambio en la equidad de propiedad de mosquiteros tratados con insecticida (ITN) en 19 países donde la malaria es endémica en el África subsahariana, antes y después del lanzamiento de la iniciativa Cover the bed net gap. Métodos Para evaluar el cambio en la equidad de propiedad de, al menos, un ITN por domicilio de distintos sectores demográficos, se utilizó información proveniente de las Encuestas de Demografía y Salud y las Encuestas de Indicadores de Malaria. Se asignaron las encuestas realizadas antes del lanzamiento (entre 2003 y 2008) como encuestas iniciales y las realizadas entre 2009 y 2014 como encuestas finales. Se realizaron análisis a nivel nacional y análisis conjuntos entre países. Los análisis conjuntos realizados en base al riesgo de transmisión de la malaria se llevaron a cabo dividiendo las zonas geográficas por riesgo bajo e intermedio o alto. A fin de evaluar los cambios en la equidad, se calcularon la curva de concentración de Lorenz y el índice de concentración (índice C). Resultados De los 19 países evaluados, 13 mostraron una equidad mejorada entre las encuestas iniciales y las finales, y dos no mostraron cambios. Cuatro países mostraron una reducción de la equidad, dos favoreciendo a los domicilios más pobres y otros dos a los más ricos. El análisis conjunto realizado en varios países mostró una mejora en la equidad (índice C de la encuesta inicial: 0,11; intervalo de confianza, IC, del 95%: de un 0,10 a un 0,11; e índice C de la encuesta final: 0,00; IC del 95%: de un -0,01 a un 0,00). Se observaron tendencias similares tanto en las zonas de riesgo bajo e intermedio como en las zonas de riesgo alto. 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