Critical appraisal of different control options and selection of appropriate interventions

Objectives of the lecture: To provide an overview of the process of option appraisal To demonstrate selection of control options according to epidemiological strata and discuss their merits and drawbacks (applicability) in the light of current knowledge To discuss possible obstacles and opportunities related to the selection of different interventions/strategies Examples

Option appraisal is a process of deciding between alternative approaches in achieving an objective with the primary aim to ensure that scarce resources are used efficiently Evaluation is assessment of a programme with the aim to find out whether it achieved its objectives The best evidence on effectiveness of public health interventions comes from randomised- control trials (RCTs)– a low number carried out in developing countries

Steps in conducting option appraisal Define the objectives of the programme List options that would achieve objectives Find evidence for the effectiveness and CE of these interventions Extrapolate available CE data to your site Determine which interventions would be feasible to implement Identified resources required

Reviews of preventive interventions range from well- established Cochrane systematic reviews to targeted reviews of specific types of interventions The Cochrane Library is a source of reliable and up-to- date information on the effects of interventions in health care and provides information and evidence for decision- makers and those receiving care Importance of quality of study design: Individual or community based RCT, quasi-experimental studies (prospective cohort, repeated cross-sectional), cohort without comparison group, convenience samples

Policy makers usually ask: what set of interventions should we utilise for prevention and control of a specific disease? Factors that need to be considered in the choice of interventions: strength of evidence for effectiveness, feasibility, acceptability and replicability to local context Others: existing infrastructure, costs, utilisation parameters, epidemiological and demographic factors, capacity to implement, quality of care and health seeking behaviours Differences in “real world”: adherence and quality of supporting systems will be lower and intervention might be given to different population groups

Economic techniques provide useful framework for appraisal and can be used to aid in the priority-setting process Cost-effectiveness (CE) research makes strong contribution to decision making about allocation of scarce resources in an efficient manner Ideally, planners would need to have access to CE information comparable across the range of strategies with clearly specified methods so that adjustments can be made for different epidemiological, economic and programme settings Factors that determine effectiveness vary from context to context - difference in epidemiological, behavioural and economic factors pose a limit to application of findings from effectiveness studies

Priority setting requires information on costs, effects and affordability The global approach to CEA was supported by the World Bank World Development Report (1993) and its background studies (Jamison et al, 1993) was an attempt to improve the process of priority setting and compare relative cost-effectiveness of different interventions WB estimated (WDR, 1993) that a minimum package of basic public and curative health interventions (each considered to be cost-effective) would cost US $12. However, it is unaffordable in many poor countries where health expenditure per capita is US $2 Critique of methods of WDR: greater social value given to middle-age group, disability weighting was based on experts’ opinion, decreased importance of preventive interventions due to discounting, effectiveness assumed to be the same across countries, methods based on mortality data alone could have been used

In developing countries, most common focus of economic evaluation of communicable disease interventions has been on tropical disease, malaria and HIV/AIDS However, researchers and funders have not taken the burden of disease as the only rationale as there have been relatively few studies on diarrhoeal diseases and vaccine-preventable diseases compared to their burden in terms of DALYs lost

Example: STI and HIV prevention and control interventions By 2004 UNAIDS estimates, 40 mil people in the world are HIV infected, 95% of infected live in developing countries Importance of heterogeneity of STI and HIV epidemics for development of interventions Subpopulations may be conceptualised as heterosexual vs homosexual; life-stage groupings; urban vs rural; ethnicity Differences in epidemics depend on when infections were introduced, their natural history and transmissibility; structure of sexual networks; demographic, social, economic and epidemiological contexts; interactions between HIV and STI pathogens

STI and HIV prevention interventions Classification categories for interventions to prevent STIs Level (target): Individual, group, community Type of intervention: behaviour change, treatment, vaccine, structural change (changes of policy, guidelines, laws, environment); screening, microbicide Outcomes measured: acquisition, complications Source: from: Manhart et al, JID 2005

Example: Importance of other factors in estimating effects and choice of interventions A community RCT in Mwanza, Tanzania, showed that community- based STI treatment (including training of primary health care workers in STD syndrome management) reduced HIV incidence by 40% after 2 years in an environment characterised by an emerging HIV epidemic (low and slowly rising prevalence), where STI treatment services are poor and where STIs are highly prevalent. However, community-based RCTs carried out in Rakai and Masaka, Uganda found no effect of STI control programme via home-based mass antibiotic treatment, which is attributed to lower risk-behaviour and the mature HIV epidemic in Uganda in 1990s

Another study used models (Bernoulli and proportionate change model) to compare estimates of cost-effectiveness for 26 HIV prevention interventions - biomedical, structural and behavioural (Cohen et al, J AIDS 2004) Two factors were identified as having the highest impact on the cost-effectiveness of different interventions: HIV prevalence of the population at risk and cost per person reached. In low-prevalence populations (heterosexuals) structural interventions were found to be the most cost-effective (mass media, condom distribution). In high-prevalence (men who have sex with men) individually focused behavioural interventions were the most cost-effective.

Choices between prevention and treatment Marseille et al and Creese et al in 2002 used CEA to argue that prevention of HIV/AIDS in sub-Saharan Africa should take priority over treatment and care (the cost per DALY gained ranged from $1 for combined treatment of STIs and condom promotion to over $1000 for HART) They estimated that for every 1 life-year gained with HAART, 28 life- years could have been gained with prevention CEA calculations lead them to wrongly accept a different value for life in rich and poor countries Decision to treat can not be based only on narrow CEA, but has to involve human considerations and wider social and economic benefits and externalities This also indicates the complex link between CEA and policy making

Limitations of studies that estimate effectiveness Participation bias – persons who participate might be more willing to change behaviours Publications bias Often non-experimental in resource-poor settings Outcomes (especially behavioural) tend to be self-reported Longer-term effectiveness is rarely assessed Lack of data in some hard to reach groups (men who have sex with men, injecting drug users, youth) Not all studies report the methods used to calculate costs Lack of common outcome measures make results difficult to compare Because of these issues, there has been a move towards model-based techniques of assessing effectiveness of interventions (however, models differ in their structure, functions and assumptions)

Undertaking a number of strategies jointly would improve the effectiveness and possibly reduce costs, due to economies of scope Such multi-component interventions have not been evaluated in the literature There have been few evaluations of structural interventions in developing countries for any public health problem One review of effectiveness of HIV prevention interventions in developing interventions published in 2000 found no single published research on HIV interventions in Eastern Europe (Merson MH et al. AIDS 2000; 14 (S2): S68-284) Importance of political support and alliances with NGOs (Thailand 100% condom promotion programme)

To enable control programmes based on better evidence, there is an urgent need to collect cost and effectiveness information specific to local epidemiological and economic conditions and health system abilities and constraints