Limits to evidence-based health policymaking: policy hurdles to structural HIV prevention in Tanzania.

Despite the well-documented role of highly co-endemic biological cofactors in facilitating HIV transmission and the availability of comparatively inexpensive tools to control them, cofactor-related interventions are only hesitantly included into African HIV prevention strategies. Against this background, this study analyzes political obstacles to policy-uptake of evidence concerning structural HIV prevention. The data used stem from fieldwork conducted in Tanzania between 2007 and 2009. They include 92 in-depth interviews with key AIDS policymakers and observations of 8 national-level policy meetings. Adopting a political economy perspective, the study shows that 1) assuming cost-aversion as a spontaneous reflex of policymakers is empirically wrong and analytically misleading, 2) that political constituencies induce a path dependence of allocative decisions inconducive to structural prevention, 3) that interventions' political attractiveness depends on the nature of their outputs and the expected temporality of political returns, 4) that policy fragmentation entailed by vertical disease control disfavours the consideration of broader causalities, and 5) that cofactor-based measures are hampered by policymakers' perception of structural prevention as being excessively complex and ultimately tantamount to poverty eradication. Confronting the policy players' reading of the Tanzanian situation with recent and classical literature on evidence-based decision-making and the politics of public health, this paper shows that, far from being strictly evidence-driven, HIV prevention policies result from a politically negotiated aggregation of competing, frequently non-optimizing rationalities. A realistic appraisal of policy processes suggests that the failure to consider the invariably political nature of HIV-related policymaking hampers the formulation of effective, politically informed strategies for positive change. Consequently, developing policy practitioners' understanding of how to effectively engage in evidence-influenced political struggles over priorities might be more instrumental in improving HIV prevention strategies than attempts to sidestep these ineradicably antagonistic controversies though technical decision tools meant to optimize health outcomes via the formulation of 'rational consensus'.