Cost-effectiveness of community-based strategies for blood pressure control in a low-income developing country: findings from a cluster-randomized, factorial-controlled trial

Abstract

Background: Evidence on economically efficient strategies to lower blood pressure (BP) from low- and middle-income countries remains scarce. The Control of Blood Pressure and Risk Attenuation (COBRA) trial randomized 1341 hypertensive subjects in 12 randomly selected communities in Karachi, Pakistan, to 3 intervention programs: (1) combined home health education (HHE) plus trained general practitioner (GP); (2) HHE only; and (3) trained GP only. The comparator was no intervention (or usual care). The reduction in BP was most pronounced in the combined group. The present study examined the cost-effectiveness of these strategies.

Methods and results: Total costs were assessed at baseline and 2 years to estimate incremental cost-effectiveness ratios based on (1) intervention cost; (2) cost of physician consultation, medications, diagnostics, changes in lifestyle, and productivity loss; and (3) change in systolic BP. Precision of the incremental cost-effectiveness ratio estimates was assessed by 1000 bootstrapping replications. Bayesian probabilistic sensitivity analysis was also performed. The annual costs per participant associated with the combined HHE plus trained GP, HHE alone, and trained GP alone were $3.99, $3.34, and $0.65, respectively. HHE plus trained GP was the most cost-effective intervention, with an incremental cost-effectiveness ratio of $23 (95 confidence interval, 6-99) per mm Hg reduction in systolic BP compared with usual care, and remained so in 97.7 of 1000 bootstrapped replications.

Conclusions: The combined intervention of HHE plus trained GP is potentially affordable and more cost-effective for BP control than usual care or either strategy alone in some communities in Pakistan, and possibly other countries in Indochina with similar healthcare infrastructure.

Figure 1

Incremental Cost-effectiveness plane at 5% discounting. Bootstrap replications showing the effect differences in change in blood pressure between randomized treatment programs versus usual care on the x-axis. An effect of larger than zero means greater reduction in BP in the treatment group. The proportions on the graphs indicate the percent of values out of the1000 replications for which effect difference was greater than 0. The y-axis shows the cost difference between intervention versus usual care. Positive values suggest the intervention is more expensive compared to usual care and vice versa. Relative to the control group (usual care) at the origin, the incremental costs are divided across the horizontal axis of the plane (higher positive, lower negative) and the incremental effect by the vertical axis (higher to the right, lower to the left). Thus, each quadrant has a different implication for the choice of intervention. Interventions with ICERs falling in the southeast quadrant would be more effective and less costly, and therefore always cost-effective relative to the comparator. Interventions with ICERs in the northwest quadrant would be less effective and more costly, and not cost-effective. An intervention with ICERs falling in the northeast quadrant would be more effective but also more costly; consequently, a trade-off between costs and effects would need to be considered, as this would represent a situation where interventions may be cost-effective compared to usual care, depending upon the value at which the ICER is considered good value for investment HHE=home health education; GP=trained general practitioner group.

Figure 1

Incremental Cost-effectiveness plane at 5% discounting. Bootstrap replications showing the effect differences in change in blood pressure between randomized treatment programs versus usual care on the x-axis. An effect of larger than zero means greater reduction in BP in the treatment group. The proportions on the graphs indicate the percent of values out of the1000 replications for which effect difference was greater than 0. The y-axis shows the cost difference between intervention versus usual care. Positive values suggest the intervention is more expensive compared to usual care and vice versa. Relative to the control group (usual care) at the origin, the incremental costs are divided across the horizontal axis of the plane (higher positive, lower negative) and the incremental effect by the vertical axis (higher to the right, lower to the left). Thus, each quadrant has a different implication for the choice of intervention. Interventions with ICERs falling in the southeast quadrant would be more effective and less costly, and therefore always cost-effective relative to the comparator. Interventions with ICERs in the northwest quadrant would be less effective and more costly, and not cost-effective. An intervention with ICERs falling in the northeast quadrant would be more effective but also more costly; consequently, a trade-off between costs and effects would need to be considered, as this would represent a situation where interventions may be cost-effective compared to usual care, depending upon the value at which the ICER is considered good value for investment HHE=home health education; GP=trained general practitioner group.

Figure 1

Incremental Cost-effectiveness plane at 5% discounting. Bootstrap replications showing the effect differences in change in blood pressure between randomized treatment programs versus usual care on the x-axis. An effect of larger than zero means greater reduction in BP in the treatment group. The proportions on the graphs indicate the percent of values out of the1000 replications for which effect difference was greater than 0. The y-axis shows the cost difference between intervention versus usual care. Positive values suggest the intervention is more expensive compared to usual care and vice versa. Relative to the control group (usual care) at the origin, the incremental costs are divided across the horizontal axis of the plane (higher positive, lower negative) and the incremental effect by the vertical axis (higher to the right, lower to the left). Thus, each quadrant has a different implication for the choice of intervention. Interventions with ICERs falling in the southeast quadrant would be more effective and less costly, and therefore always cost-effective relative to the comparator. Interventions with ICERs in the northwest quadrant would be less effective and more costly, and not cost-effective. An intervention with ICERs falling in the northeast quadrant would be more effective but also more costly; consequently, a trade-off between costs and effects would need to be considered, as this would represent a situation where interventions may be cost-effective compared to usual care, depending upon the value at which the ICER is considered good value for investment HHE=home health education; GP=trained general practitioner group.