Print version ISSN 0042-9686
Bull World Health Organ vol.86 n.11 Genebra Nov. 2008
Impact de la participation dont s'acquittent les utilisateurs des services de santé dans les pays à revenu faible ou moyen : Les données sont-elles solides?
Impacto del cobro de honorarios a los usuarios en el uso de los servicios de salud en los países de ingresos bajos y medios: grado de evidencia
Mylene Lagarde1; Natasha Palmer
London School of Hygiene and Tropical Medicine, Keppel Street, London, WC1E 7HT, England
OBJECTIVE: To assess the effects of user charges on the uptake of health services in low- and middle-income countries.
METHODS: A systematic search of 25 social science, economics and health literature databases and other sources was performed to identify and appraise studies on the effects of introducing, removing, increasing or reducing user charges on the uptake of various health services in low- and middle-income countries. Only experimental or quasi-experimental study designs were considered: cluster randomized controlled trials (C-RCT), controlled " before and after" (CBA) studies and interrupted time series (ITS) studies. Papers were assessed in which the effect of the intervention was measured in terms of changes in service utilization (including equity outcomes), household expenditure or health outcomes.
FINDINGS: Sixteen studies were included: five CBA, two C-RCT and nine ITS. Only studies reporting effects on health service utilization, sometimes across socioeconomic groups, were identified. Removing or reducing user fees was found to increase the utilization of curative services and perhaps preventive services as well, but may have negatively impacted service quality. Introducing or increasing fees reduced the utilization of some curative services, although quality improvements may have helped maintain utilization in some cases. When fees were either introduced or removed, the impact was immediate and abrupt. Studies did not adequately show whether such an increase or reduction in utilization was sustained over the longer term. In addition, most of the studies were given low-quality ratings based on criteria adapted from those of the Cochrane Collaboration's Effective Practice and Organisation of Care group.
CONCLUSIONS: There is a need for more high-quality research examining the effects of changes in user fees for health services in low- and middle-income countries.
OBJECTIF: Evaluer les effets de la participation à la charge de l'utilisateur sur le recours aux services de santé dans les pays à revenu faible ou moyen.
MÉTHODES: Une revue systématique de 25 bases de données relatives aux sciences sociales, à l'économie et à la santé, ainsi que d'autres sources, a été effectuée pour identifier et évaluer les études concernant les effets de l'introduction, de la suppression, de l'augmentation ou de la réduction des frais à la charge des utilisateurs sur le recours aux divers services de santé, dans les pays à revenu faible ou moyen. Seules les études de type expérimental ou quasi-expérimental ont été prises en compte : il s'agissait notamment d'essais contrôlés randomisés par grappes, d'études contrôlées «avant et après» et d'analyses de séries temporelles interrompues. On a également évalué des articles mesurant les effets de ce type d'intervention sur l'évolution du recours aux services sanitaires (y compris les résultats en termes d'équité), des dépenses des ménages ou des résultats sanitaires.
RÉSULTATS: Seize études ont été prises en compte : cinq études contrôlées avant et après, deux essais contrôlés et randomisés par grappes et neuf analyses de séries temporelles interrompues. On n'a retenu que des études rapportant des effets sur le recours aux services de santé, dans certains cas parmi des groupes socioéconomiques. On a constaté que la suppression ou la réduction des frais à la charge des utilisateurs se traduisait par un plus grand recours aux services curatifs et potentiellement aux services préventifs, mais aussi parfois par une détérioration de la qualité des services. Le fait d'introduire ou d'augmenter de tels frais diminuait le recours à certains services curatifs, bien que des améliorations de la qualité de ces services aient pu contribuer à maintenir leur niveau d'utilisation dans certains cas. Lors de l'introduction ou de la suppression d'une participation à la charge des utilisateurs, l'impact a été immédiat et brusque. Les études ne montraient pas suffisamment bien si l'augmentation ou la diminution du recours observée perdurait à long terme. De plus, la plupart d'entre elles ont été jugées de basse qualité selon des critères adaptés d'après le Cochrane Collaboration's Effective Practice and Organisation of Care Group.
CONCLUSION: Des travaux de recherche de meilleure qualité sont nécessaires pour examiner les effets de modifications des frais à la charge des bénéficiaires des services de santé dans les pays à revenu faible ou moyen.
OBJETIVO: Evaluar los efectos de los honorarios cobrados a los usuarios sobre el uso de los servicios de salud en los países de ingresos bajos y medios.
MÉTODOS: Se llevó a cabo una búsqueda sistemática en 25 bases de datos y otras fuentes de bibliografía sobre ciencias sociales, economía y salud a fin de identificar y evaluar los estudios realizados sobre los efectos de introducir, suprimir, aumentar o reducir las tarifas cobradas a los usuarios en la utilización de diversos servicios de salud en los países de ingresos bajos y medios. Sólo se tuvieron en cuenta los estudios experimentales o cuasiexperimentales: ensayos controlados aleatorizados por conglomerados (ECA-G), estudios controlados " antes y después" (CAD) y estudios de series temporales interrumpidas (STI). Se evaluaron los artículos en los que se habían medido los efectos de la intervención en la utilización de los servicios (incluidos los resultados de equidad), el gasto de los hogares o los resultados sanitarios.
RESULTADOS: Se consideraron 16 estudios: 5 CAD, 2 ECA-G y 9 STI. Sólo se identificaron los estudios en que se habían notificado efectos sobre la utilización de los servicios de salud, a veces en distintos grupos socioeconómicos. Se observó que la supresión o reducción de los honorarios cobrados a los usuarios aumentaba la utilización de los servicios curativos y podía aumentar también la de los servicios preventivos, pero esas medidas pueden tener un impacto negativo en la calidad de los servicios. La introducción de honorarios o el aumento de los mismos redujeron la utilización de algunos servicios curativos, aunque las mejoras de la calidad pueden haber ayudado a mantener la utilización en algunos casos. Los efectos de la introducción o supresión de los honorarios fueron inmediatos y pronunciados, pero los estudios no revelaron con claridad si ese aumento o reducción de la utilización se mantenía a largo plazo. Además, la mayoría de los estudios fueron clasificados como de baja calidad de acuerdo con los criterios adaptados a partir de los establecidos por el Grupo de Eficacia de la Práctica y Organización de la Atención de la Colaboración Cochrane.
CONCLUSIÓN: Es necesario emprender investigaciones de mayor calidad para determinar los efectos de los cambios en los honorarios pagados por los usuarios sobre los servicios de salud en los países de ingresos bajos y medios.
Access to basic health services of acceptable quality is still denied to many of the world's poorest people.1 Against a backdrop of severely underfunded health systems,1,2 governments are faced with a dilemma. Payments for health services, in the form of user charges, are likely to present a barrier to access. Yet, a shortage of resources at the facility level is a contributor to failure to deliver quality services, and this also presents a barrier to access. Some have argued that user charges can generate vital resources at the local level and help provide good quality services;35 others have highlighted their negative effects, particularly on equity;69 Recently, several international campaigns have advocated the removal of user fees, especially for primary care services.1,10
Some recent articles have underlined the paucity of evidence on the effectiveness of policy interventions in low-income countries;11,12 others have noted the importance of systematic reviews for understanding health systems.13 Despite the central importance of the user-fee debate, no systematic review has examined the quality of the empirical evidence on this topic. To redress this imbalance, this review set out to assess the quality of the existing evidence on the impact of user fees on health service utilization, household expenditures and health outcomes in low- and middle-income countries.
Scope of the review
User fees refer to a financing mechanism that has two main characteristics: payment is made at the point of service use and there is no risk sharing. User fees can entail any combination of drug costs, supply and medical material costs, entrance fees or consultation fees. They are typically paid for each visit to a health service provider, although in some cases follow-up visits for the same episode of illness can be covered by the initial payment. This review aimed to assess the effect on health service utilization of introducing, removing, increasing or decreasing user fees in low- and middle-income countries.
Search strategy and inclusion criteria
We searched 25 databases covering the social science, economics and health literature. We also searched the reference lists of all relevant articles, the web sites of related research centres or institutions (lists of sources searched are available from the authors upon request) and existing reviews.1419 The search strategy combined looking for terms in subject headings and within the text pertaining to health financing (" health financing" , " user charges" , " user fees" , " cost recovery" , " direct payment" , " drug revolving fund" , " fee" ) and outcomes (" utilization" , " access to services" , " health expenditures" , etc.). No limitation on date or publication language was applied. Only studies from low- and middle-income countries, as defined by the World Bank, were included.
Only experimental or quasi-experimental study designs were included cluster randomized controlled trials (C-RCTs), controlled " before and after" (CBA) studies and interrupted time series (ITS) studies (Table 1) as suggested by the Effective Practice and Organisation of Care (EPOC) group of the Cochrane Collaboration, where this review was registered. Indeed, such designs are known to provide the most reliable measures of effect. Papers were assessed only if the effect of the intervention was measured in terms of either changes in utilization, household expenditure, health outcome or equity. Both authors independently sifted the titles and abstracts of publications for retrieval. In case of disagreement, full-text articles were retrieved and examined. All retrieved articles were then independently reviewed by the two authors, and agreement was reached over whether they fulfilled the criteria for inclusion in the review.
Reanalysis of data
We found several studies that had longitudinal data on utilization but had not performed a time series analysis.2026 To be able to include these, we relaxed the original definition of ITS27 (Table 1) and set out to reanalyse the data appropriately. When they were not directly reported in the paper, original data series were requested from the authors. Whenever the authors could not be found or did not respond, we attempted to reconstruct data series by scanning graphs.1
Data series were then examined with the following segmented regression model to control for secular trends and potential serial correlation of data, and to detect any significant changes after the introduction of the new policy:
Yt = β0 + β1 × Preslope + β2 × Intervention + β3 × Postslope + et
where Yt is the outcome variable at time t. Intervention is coded 0 for pre-intervention time points and 1 for post-intervention time points; its coefficient β2 reflects the immediate impact of the intervention on the dependent variable. Preslope is a continuous variable indicating time from the start of the study up to the intervention (if the intervention occurred at the nth period, preslope is coded sequentially from 1 to n before the intervention and remains equal to n for the rest of the series). It thereby captures the structural trend that has started before the intervention. Postslope is coded 0 up to the last point before the intervention phase and coded sequentially from 1 thereafter. Its coefficient β3 therefore reflects the trend or growth rate in outcome after the intervention. When auto-correlation was detected by the Durbin-Watson test, it was corrected with a PraisWinsten regression.
In addition, to provide more comparable results, we computed price elasticities (ep) for studies reporting changes in user fees, and " net" elasticities for those with a control site. We also computed the statistical significance of the observed effects if it was not reported in the original paper.
Data extraction and quality assessment
Quality criteria were adapted from those suggested by the EPOC group of the Cochrane Collaboration (Table 2). When a study presented unsatisfactory or unclear elements for two or more criteria, it was scored as being of " low" quality. When only one criterion was unclear or unmet, it was scored as being of " moderate" quality, and when all elements were satisfied, the study was considered as being of " high" quality. For each included study, both authors extracted data and assessed quality. They then reviewed one another's conclusions. Discrepancies were resolved by discussion.
Description of studies
The initial database search generated over 24 000 references. An initial sift of titles and abstracts led to the inclusion of 243 documents for further investigation (Fig. 1 provides more details on the search strategy). Sixteen studies met our inclusion criteria. We only found studies reporting effects on health service utilization. None reported an effect on expenditures or health outcomes, and two reported effects on utilization by different socioeconomic groups.
Eight papers presented data on the effects of introducing user fees (Table 3), five on the effects of removing fees (Table 4) and five on the effects of decreasing or increasing fees (Table 5 and Table 6). Some papers reported results from specifically designed studies,4,2832 while others sought to analyse the effect of nationally- implemented strategies using routine data.2026,3335
Study settings varied considerably (type of service, type of facility, type of payment). A range of utilization measures were reported as outcomes, including new visits, registrations, weekly/quarterly/monthly attendance, outpatient and/or inpatient attendance. As a result, a narrative approach to reporting the results has been adopted.
Impact of removing user fees
Five studies used longitudinal data to report the effects of abolishing user fees on utilization. These were all reanalysed.22,2426,35 Results from the reanalysis confirm an abrupt increase in the utilization of curative services following fee removal (Table 7, available at: http://www.who.int/bulletin/volumes/86/11/07-049197/en/index.html). This abrupt increase was rarely followed by a sustained increase in utilization growth. In most instances, no significant change was recorded in attendance for preventive services,22,24,35 which were usually already free. However, several data series showed that after fees were removed, the growth in preventive service utilization significantly increased (or, in South Africa, declined at a more modest rate), which could be interpreted as a long-term trickle-down effect of fee removal (Table 7). However, the quality of the data from which these conclusions were drawn was judged to be low due to the presence of confounding factors (concurrent policy changes), the questionable quality of routine data or small sample sizes.
Impact of introducing user fees
Eight studies examined the effect of introducing user fees: two CBA studies,4,29 one C-RCT32 and five ITS studies.2024 ITS studies suggested that policies that introduced user fees decreased health service uptake (Table 8, available at: http://www.who.int/bulletin/volumes/86/11/07-049197/en/index.html). Indeed, the reanalysis showed a sharp single step down in utilization levels for curative services in Kenya.21,22,24 A similar, though less significant change was observed in Burkina Faso.20 Data from Papua New Guinea23 showed a decrease in utilization of preventive services, more striking when compared to the concomitant utilization increase in free facilities. Although growth in service uptake was often greater after the policy change, suggesting potential positive outcomes in the long run, this was not a statistically significant result. Again, the quality of the data and analysis from which these conclusions were drawn was judged to be low. In particular, in all cases changes in fees occurred at the same time as economic crises and/or other changes in the health system, reducing the extent to which one could attribute changes to fees alone.
The two CBA studies4,29 examined the effects of introducing user fees alongside quality improvements, and both found that this increased utilization for the poorest groups. However, both studies also had significant weaknesses in terms of design and analysis. In a C-RCT of good quality, Kremer and Miguel32 showed that uptake of worm-prevention treatment in Kenyan schools fell from 75% to 19% after fees were introduced. In a regression analysis, the authors found that the introduction of cost-sharing was responsible for the major part of this reduction in uptake.
Impact of decreasing user fees
Evidence from two studies28,31 on the effect of decreasing fees suggested an increase in utilization (Table 9). Abdu et al.31 found that decreasing user fees by 25% and 75% led to a more than proportionate change in the number of pregnant women and children seen in health centres in the Sudan. This study again has several methodological limitations.31 Ojeda et al.28 reported that decreasing the price of intrauterine devices in Colombia led to an increase in the number of users and indicated a highly sensitive price elasticity of demand. However, high inflation at the time in Colombia may have caused people to overestimate the real fall in price.
Impact of increasing user fees
We included three studies reporting the effects of increasing user fees. One33 studied an increase of user fees in the public sector (Table 8) and two30,34 studied their effect in private facilities (Table 10). Data from Lesotho33 showed that increasing user fees led to a drop in utilization in the public sector, while uptake of services in private not-for-profit facilities did not change. In Gabon,34 data from two increases in fees in a private hospital showed that demand became increasingly sensitive to price, which suggests a threshold effect. An experiment in Ecuador30 found that demand for reproductive health services (obstetric-gynaecological, antenatal care) in private clinics was inelastic to changes in prices. However, this study was again subject to limitations due to confounding factors (high inflation may have confused real price variations) and a failure to follow the initial experimental design.
This review is the first attempt to systematically assess the quality of existing evidence on the subject of charging for health services in low-income countries. It differs from previous reviews1517 in using a formal protocol and systematically appraising the evidence.
There is some limited evidence from the papers reviewed to suggest that removing user fees increases the utilization of curative health-care services, usually in the form of one sharp step-up following fee removal. This policy change may also have a positive impact on the uptake of preventive services in the long run.
As for the introduction of user fees, there is limited evidence that it decreases utilization, again in the form of one sharp reduction. It is unclear from any study if this effect extends beyond this initial drop. Two studies suggested that the combination of user fees and improvements in quality can increase utilization.
These findings broadly support the view that user fees present a barrier to access to curative health services for those groups that would be eligible to pay for them. They concur with those of some of the non-systematic reviews on user fees that have been completed.1517 However, we feel that there are several important questions in this area that remain unanswered, and it is important to note that all but one of the studies had significant weaknesses.
Weaknesses of the available evidence
It must be stressed that the quality of the available evidence was low. One study32 was found to be of good quality, while all others were potentially biased. Even studies that have been highly influential and often quoted4,29 failed our quality appraisal. A particular weakness was that only two studies looked at differential impact across population groups.4,29 Most studies on routine data could not assess the equity impact of the reforms described.
Most studies providing longitudinal data (and reanalysed as ITS) were unable to isolate changes in charges for health services from other concurrent changes occurring in, or outside of, the health system. A similar problem in two experimental studies was that high inflation may have confused the effects of price variations.28,30 A key problem for the CBA studies was non-equivalence between control and intervention sites (Table 3 and Table 4). In one study there may also have been problems controlling whether free care was really free in control areas.36
These quality shortcomings, in combination with such a limited number of studies on each topic, mean that many questions remain. Key questions include the effects of fee changes on the quality of care, drug use and health worker motivation as well as utilization. The question of which patients increase or decrease their utilization of health services, and for what health conditions, is also almost totally unanswered. The longer term impacts of fee introduction or removal have also not been adequately measured. There are many difficulties associated with answering such questions in the " noisy" setting of health systems. However, there remains considerable scope for improvement in the quality of research and analysis around this area.
Strengths and weaknesses of the review
This review is the first of its type to address such an important policy question for health financing. The scope of the review was wide. Some papers dealt with the change in price of a specific good, while others dealt with charges for basic health services more generally. Studies also covered both public- and private-sector charges. Some are the result of specially-designed experiments; others are attempts to study the effects of a " real world" policy change. The result is that our findings are heterogeneous and hard to summarize quantitatively. There may be value in narrowing down the scope of such reviews in the future, although this must be balanced against the paucity of papers on any given subject.
Criteria such as those suggested by the EPOC group are immensely valuable in lending rigour to the review process but should perhaps be modified to reflect the difficulties of isolating cause and effect in some of the settings we have described, where policy changes usually parallel other events and are dependent on broader contextual factors.37 This raises the question of whether the standards that we applied are reasonable in the setting of health-systems research, where understanding the reasons for success or failure of social interventions is as critical and informative as measuring their effects. Observational or qualitative case studies,38 studies of policy implementation39 and costing studies play an important role in helping understand how policies get implemented. It is also important to stress the value of many studies that were not included in this review because they were not designed to offer a direct measure of effect, such as studies on health-seeking behaviour7,40,41 or benefit-incidence analyses.42 Recently, several developments have emerged that translate the principles of systematic reviews into health-system research, while assessing qualitative and quantitative evidence43 or accounting for the complexity of interventions.44 In the user-fee case, such complexity is demonstrated by the desirability of studying utilization, equity, quality and implementation simultaneously to really understand effect.
At present, the magnitude and heat of the debate over user fees are not matched by efforts to strengthen the evidence base on the topic. Despite a sizeable literature published on this issue and some vigorous debate spanning several decades, there is still a scarcity of good quality evidence. Two questions remain. Why is this the case? What can be done?
Good impact evaluations seem difficult to apply to health systems.45 This is partly for economic reasons (they are costly and labour intensive) and partly for ethical and political ones (it is difficult to give services to some communities and not to others in order to create control groups). Such research may be overly burdensome and time consuming, while changes in policies are often driven by political agendas and happen quickly. Finally, very little large-scale research funding has been available in the area of health financing or health systems research.
Evidence from carefully designed impact evaluations should be advocated, and the recent effort of the Centre for Global Development to establish an International Initiative for Impact Evaluation is to be welcomed.11 In the meantime, several simple steps can be taken by researchers to improve the quality of research and evidence in this area:
- lobby for policy-makers and donors to design prospective evaluations before rolling out national policy changes, such as introducing or removing user fees;
- try to identify control sites;
- use appropriate statistical and econometric methods to analyse data;
- combine quantitative analysis of effect with qualitative information describing context and implementation issues;
- seek to measure the equity effect of changes in charging policy.
Funding: This work was funded by the Bill & Melinda Gates Foundation.
Competing interests: None declared.
1. Our common interest: report of the Commission for Africa. London: Commission for Africa; 2005. [ Links ]
2. Macroeconomics and health: investing in health for economic development: Report of the Commission on Macroeconomics and Health. Geneva: WHO; 2001. [ Links ]
3. Ellis RP. The revenue generating potential of user fees in Kenyan government health facilities. Soc Sci Med 1987;25:995-1002. PMID:3423850 doi:10.1016/0277-9536(87)90004-9 [ Links ]
4. Litvack JI, Bodart C. User fees plus quality equals improved access to health care: results of a field experiment in Cameroon. Soc Sci Med 1993;37:369-83. PMID:8356485 doi:10.1016/0277-9536(93)90267-8 [ Links ]
5. Financing the health sector in developing countries: an agenda for reform. Washington, DC: The World Bank; 1987. [ Links ]
6. Gilson L. Government health care charges: is equity being abandoned? A discussion paper. London: London School of Hygiene and Tropical Medicine; 1988. [ Links ]
7. Gertler P, Locay L, Sanderson W. Are user fees regressive? The welfare implications of health care financing proposals in Peru. J Econom 1987;36:67-88. doi:10.1016/0304-4076(87)90044-3 [ Links ]
8. Yoder RA. Are people willing and able to pay for health services? Soc Sci Med 1989;29:35-42. PMID:2740926 doi:10.1016/0277-9536(89)90125-1 [ Links ]
9. Russell S, Gilson L. User fee policies to promote health service access for the poor: a wolf in sheep's clothing? Int J Health Serv 1997;27:359-79. PMID:9142607 [ Links ]
10. User fees: paying for health services at the point of use [position paper]. London: Save the Children, UK; 2005. [ Links ]
11. Savedoff WD, Levie R, Birdsall N. When will we ever learn? Improving lives through impact evaluation. Washington, DC: Center for Global Development; 2006. [ Links ]
12. Duflo E, Glennerster R, Kremer M. Randomized evaluations of interventions in social science delivery. Development Outreach March 2004. Available from: http://www1.worldbank.org/devoutreach/march04/ [accessed on 3 September 2008] [ Links ].
13. Lavis J, Davies H, Oxman A, Denis JL, Golden-Biddle K, Ferlie E. Towards systematic reviews that inform health care management and policy-making. J Health Serv Res Policy 2005;10 S1;35-48. PMID:16053582 doi:10.1258/1355819054308549 [ Links ]
14. Creese AL. User charges for health care: a review of recent experience. Health Policy Plan 1991;6:309-19. PMID:10115978 doi:10.1093/heapol/6.4.309 [ Links ]
15. Sepehri A, Chernomas R. Are user charges efficiency- and equity-enhancing? A critical review of economic literature with particular reference to experience from developing countries. J Int Dev 2001;13:183-209. doi:10.1002/jid.726 [ Links ]
16. Hutton G. Is the jury still out on the impact of user fees in Africa? A review of the evidence from selected countries on user fees and determinants of health service utilisation. East Afr Med J 2004;81:45-60. [ Links ]
17. James CD, Hanson K, McPake B, Balabanova D, Gwatkin D, Hopwood I, et al. To retain or remove user fees? Reflections on the current debate in low- and middle-income countries. Appl Health Econ Health Policy 2006;5:137-53. PMID:17132029 doi:10.2165/00148365-200605030-00001 [ Links ]
18. McPake B. User charges for health services in developing countries: a review of the economic literature. Soc Sci Med 1993;36:1397-405. PMID:8511628 doi:10.1016/0277-9536(93)90382-E [ Links ]
19. Gilson L. The lessons of user fee experience in Africa. Health Policy Plan 1997;12:273-85. PMID:10176263 [ Links ]
20. Ridde V. Fees-for-services, cost recovery, and equity in a district of Burkina Faso operating the Bamako Initiative. Bull World Health Organ 2003;81:532-8. PMID:12973646 [ Links ]
21. Mbugua JK, Bloom GH, Segall MM. Impact of user charges on vulnerable groups: the case of Kibwezi in rural Kenya. Soc Sci Med 1995;41:829-35. PMID:8571154 doi:10.1016/0277-9536(94)00400-N [ Links ]
22. Collins D, Quick JD, Musau SN, Kraushaar K, Hussein IM. The fall and rise of cost sharing in Kenya: the impact of phased implementation. Health Policy Plan 1996;11:52-63. PMID:10155878 doi:10.1093/heapol/11.1.52 [ Links ]
23. Benjamin AL, Sapak P, Purai JK. User charges and utilisation of obstetric services in the National Capital District, Papua New Guinea. Pac Health Dialog 2001;8:38-43. PMID:12017833 [ Links ]
24. Moses S, Manji F, Bradley JE, Nagelkerke NJ, Malisa MA, Plummer FA. Impact of user fees on attendance at a referral centre for sexually transmitted diseases in Kenya. Lancet 1992;340:463-6. PMID:1354792 doi:10.1016/0140-6736(92)91778-7 [ Links ]
25. Burnham GM, Pariyo G, Galiwango E, Wabwire-Mangen F. Discontinuation of cost sharing in Uganda. Bull World Health Organ 2004;82:187-95. PMID:15112007 [ Links ]
26. Wilkinson D, Gouws E, Sach M, Karim SS. Effect of removing user fees on attendance for curative and preventive primary health care services in rural South Africa. Bull World Health Organ 2001;79:665-71. PMID:11477970 [ Links ]
27. McDowall D, McCleary R, Meidinger E, Hay R. Interrupted time series analysis. Newbury Park, CA: Sage Publications; 1980. [ Links ]
28. Ojeda G, Murad R, Leon F, Williams T. Testing pricing payment systems to improve access and cost-recovery from Norplant. In: Association Pro-Bienestar de la Familia Colombiana (PROFAMILIA), PCII, International Planned Parenthood Federation Western Hemisphere Region (IPPF/WHR). USAID, Washington, DC; 1994. [ Links ]
29. Diop F, Yazbeck A, Bitrán R. The impact of alternative cost recovery schemes on access and equity in Niger. Health Policy Plan 1995;10:223-40. PMID:10151841 doi:10.1093/heapol/10.3.223 [ Links ]
30. Bratt JH, Weaver MA, Foreit J, De Vargas T, Janowitz B. The impact of price changes on demand for family planning and reproductive health services in Ecuador. Health Policy Plan 2002;17:281-7. PMID:12135994 doi:10.1093/heapol/17.3.281 [ Links ]
31. Abdu Z, Mohammed Z, Bashier I, Eriksson B. The impact of user fee exemption on service utilization and treatment seeking behaviour: the case of malaria in Sudan. Int J Health Plann Manage 2004;19 Suppl 1;S95-106. PMID:15686063 doi:10.1002/hpm.777 [ Links ]
32. Kremer M, Miguel E. The illusion of sustainability. Q J Econ 2007;122:1007-65. doi:10.1162/qjec.122.3.1007 [ Links ]
33. Bennett S. The impact of the increase in user fees: a preliminary investigation. Lesotho Epidemiol Bull 1989;4:29-37. [ Links ]
34. Issifou S, Kremsner PG. Impact of increasing consultation fees on malaria in Africa. Wien Klin Wochenschr 2004;116:332-3. PMID:15237660 [ Links ]
35. Nabyonga J. Desmet M, Karamagi H, Kadama PY, Omaswa FG, Walker O. Abolition of cost-sharing is pro-poor: evidence from Uganda. Health Policy Plan 2005;20:100-8. PMID:15746218 doi:10.1093/heapol/czi012 [ Links ]
36. Ellis RP, Chawla M. Demand side impacts: experiment in health care cost recovery in Niger. Bethesda, MD: Abt Associates; 1994. [ Links ]
37. McPake B, Hanson K, Mills A. Community financing of health care in Africa: an evaluation of the Bamako initiative. Soc Sci Med 1993;36:1383-95. PMID:8511627 doi:10.1016/0277-9536(93)90381-D [ Links ]
38. Russell S. Illuminating cases: understanding the economic burden of illness through case study household research. Health Policy Plan 2005;20:277-89. PMID:16000367 doi:10.1093/heapol/czi035 [ Links ]
39. Gilson L, McIntyre D. Removing user fees for primary care in Africa: the need for careful action. BMJ 2005;331:762-5. PMID:16195296 doi:10.1136/bmj.331.7519.762 [ Links ]
40. Sauerborn R, Nougtara A, Latimer E. The elasticity of demand for health care in Burkina Faso: differences across age and income groups. Health Policy Plan 1994;9:185-92. PMID:15726780 doi:10.1093/heapol/9.2.185 [ Links ]
41. Pannarunothai S, Mills A. The poor pay more: health-related inequality in Thailand. Soc Sci Med 1997;44:1781-90. PMID:9194240 doi:10.1016/S0277-9536(96)00287-0 [ Links ]
42. O'Donnell O, van Doorslaer E, Rannan-Eliya R, Somanathan A, Adhikari SR, Harbianto D, et al. Who benefits from public spending on health care in Asia? EQUITAP project [working paper no. 3]. 2005. [ Links ]
43. Dixon-Woods M, Bonas S, Booth A, Jones DR, Miller T, Sutton AJ, et al. How can systematic reviews incorporate qualitative research? A critical perspective. Qual Res 2006;6:27-44. doi:10.1177/1468794106058867 [ Links ]
44. Pawson R, Greenhalgh T, Harvey G, Walshe K. Realist review a new method of systematic review designed for complex policy interventions. J Health Serv Res Policy 2005;10 Suppl 1;21-34. PMID:16053581 doi:10.1258/1355819054308530 [ Links ]
45. Ranson MK, Sinha T, Morris SS, Mills AJ. CRTs cluster randomized trials or " courting real troubles" : challenges of running a CRT in rural Gujarat, India. Can J Public Health 2006;97:72-5. PMID:16512334 [ Links ]
(Submitted: 2 November 2007 Revised version received: 4 April 2008 Accepted: 10 April 2008)