Cost-Effectiveness of Community-Based Strategies for Blood Pressure Control in a Low-Income Developing CountryClinical Perspective
Findings From a Cluster-Randomized, Factorial-Controlled Trial
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.
Cardiovascular diseases (CVD) have become the leading cause of death worldwide, and will particularly affect younger adults in developing countries, with major adverse consequences for national economies. Hypertension confers the highest attributable risk of death from CVD.1
Clinical Perspective on p 1625
The burden of hypertension has reached epidemic proportions in Indo-Asian countries, affecting a third of adults in Pakistan.2 However, public spending on health, especially chronic disease prevention, remains abysmally low in the face of competing priorities.3 Private providers are the frontline caregivers, and are visited frequently. However, serious deficiencies have been identified in their knowledge and practices with regard to the management of hypertension.4 Furthermore, there are no national strategies for the control of hypertension or similar efforts to enhance care by private providers. As highlighted in the recent Institute of Medicine Report on Cardiovascular Diseases in low- and middle-income countries, advocating both public and private sector changes requires locally obtained relevant empirical evidence on sustainable, cost-effective, and affordable population-based strategies for the prevention and control of hypertension, which is scarce.5 Recently, we reported the results of a large cluster-randomized factorial design trial on community-based strategies of home health education (HHE) and training of general practitioners (GPs) to control high blood pressure (BP).6 We found that BP declined in all groups, but the reduction was most pronounced in those randomized to the combination of both strategies compared with either intervention or no intervention.
However, neither the cost nor the cost-effectiveness of the interventions was reported.5 This information is essential for policymakers and health planners because clinically effective interventions may not necessarily represent value for money compared with the alternatives studied in this resource-poor country.7
We therefore conducted these analyses to determine (1) the cost of the interventions from the affordability perspective of the policymakers and (2) the incremental cost-effectiveness of the total healthcare costs related to the interventions compared with usual care in terms of per mm Hg reduction in BP from the societal perspective. An intervention cost from the policymakers' perspective within 10% of the existing national healthcare (government spending) budget was considered affordable.8 The lowest incremental cost-effectiveness ratio (ICER) (most BP reduction at least total healthcare cost relative to usual care) that was also significantly different compared with usual care (ie, bootstrapped 95% confidence intervals [CIs] also consistent with the mean value in direction and magnitude) was considered most cost-effective. We hypothesized that the combined HHE plus GP intervention would be more cost-effective than single interventions or usual care.
The Control of Blood Pressure and Risk Attenuation (COBRA) trial was a cluster randomized, controlled trial with a 2×2 factorial design to determine the impact of family-based HHE and/or special training of GPs on the BP levels of adults aged ≥40 years with hypertension (http://www.clinicaltrials.gov; unique identifier NCT00327574).6 The sampling frame and study design details have been described previously.6 Briefly, multistage cluster sampling techniques were used to randomly select 12 communities (with ≈250 households each) from middle- to low-income areas in Karachi. Individuals aged ≥40 years residing in the 12 clusters with known hypertension or with consistently elevated BP on 2 separate visits (mean of last 2 of 3 measurements of systolic pressure ≥140 mm Hg or mean diastolic pressure ≥90 mm Hg) were eligible for inclusion in the study. The 12 clusters were then randomly assigned to 4 groups of 3 clusters each: HHE, trained GP, HHE plus trained GP, and no intervention (Table 1).
Home Health Education
Six community health workers (1 for each cluster) trained over 6 weeks provided advice at 3-month intervals on the importance of engaging in moderate physical activity; maintaining normal body weight; reducing salt intake; maintaining an adequate intake of potassium; consuming a diet rich in fruit, vegetables, and low-fat dairy products and low in saturated and total fat (including sample recipes for culturally acceptable and economically feasible food products); and smoking cessation.9 This intervention was modeled on the existing Lady Health Workers Program in Pakistan. The details of training have been published previously.6
All GPs in the 6 study areas assigned to this intervention were invited for training, with the realistic aim to train at least two thirds of all GPs from each area. The annual training was a 1-day session focused on standard treatment for the management of hypertension, based on the Seventh Report of the Joint National Committee and the Fourth Working Party of the British Hypertension Society guidelines modified for the Indo-Asian population.10,11
All study participants aged ≥40 years with hypertension were advised to consult a local GP. Those in the clusters randomized to the trained GP arm were given a list of trained GPs within their cluster. However, GP selection remained the choice of the participants. There was no provision for supplying medications or reimbursing fees for healthcare services in the study. The participation by subjects and GPs was voluntary.
Screening and Recruitment
All households in each cluster were visited, and informed consent was obtained for screening from all adults aged ≥40 years, who then underwent measurement of BP 3 times with a calibrated automated device (Omron HEM-737 IntelliSense; Omron Healthcare Inc, Vernon Hills, IL) in the sitting position after 5 minutes of rest. Those with an elevated BP and not on antihypertensive medication were visited again for remeasurement of BP 1 to 4 weeks after the initial visit. If mean BP remained elevated, these individuals were invited to participate. In addition, those with known hypertension were also invited to participate, irrespective of measured BP.
Hypertensive adults were evaluated by trained field staff, masked to randomization status, at baseline and at 4-month intervals when 3 consecutive BP readings were taken. Information on diet (food frequency and expenditure on fruits and vegetables), physical activity (international physical activity questionnaire), current antihypertensive medications, frequency of visits to health providers in the last 2 weeks, expenditure on healthcare costs (provider fee, medications, and laboratory costs), and any hospitalizations was collected. Information on days of work lost because of illness during this period was recorded. BP was measured as described above. The planned median duration of follow-up was 2 years.
We estimated the cumulative intervention costs over 2 years. These costs included personnel, equipment, and training material and supplies for development of curricula, transport, and other operational expenses over 2 years (Table 2). Personnel costs for the interventions included salaries and fringe benefits of faculty, a nutritionist (for HHE), and community health workers (7 full-time workers for HHE and 6 part-time field workers for the trained GP group). To account for office rent and maintenance, an administrative cost of 30% was applied to intervention costs. Because 1 of the goals was to assess affordability from the policymakers' perspective and implications for public funds, only the intervention cost was used for this purpose.
The cost-effectiveness analyses were performed from a societal perspective and therefore needed to account for total healthcare costs. These costs included the cost of intervention, patient costs for healthcare and related lifestyle (diet), and productivity losses. The patient costs for healthcare included payments made by patients to the healthcare provider, the cost of purchasing medications, and expenditures for diagnostics. Patient data on costs were collected from participants at baseline and final visit by questionnaire. The questionnaire was administered in the homes of respondents by trained interviewers. Participants (from all 4 groups) were asked to provide detailed information on any medical consultations, medications purchased, medical tests conducted, and periods of hospitalization during the previous 2 weeks. These cost data were annualized to determine the direct annual healthcare cost for all 4 groups at baseline and final follow-up visit (Table 3). This rationale was consistent with our analysis of the primary effectiveness outcome of change in BP, as reported previously.6 For the cost-effectiveness analysis, the difference in annualized cost from baseline to follow-up for each group was projected over 2 years, with adjustment for inflation.
The cost of fruit and vegetables was also included in the societal aspect of lifestyle modification. Information on fruits and vegetables and meat purchased by the household during the previous 2 weeks was collected, and because interventions were delivered at the community level, the denominator for per-patient calculation was all subjects aged ≥5 years.
In accordance with the recommendation of Gold et al12 in regard to the importance of accounting for the patients' and caregivers' time, values for productivity losses were imputed for the opportunity costs to participants and caregivers, irrespective of whether or not they were engaged in paid employment. We used the average market wage rate for men and women in urban Sindh (Government of Pakistan, 2009) as the value of time lost.12,13
Productivity losses resulting from illness and treatment were imputed for participants and projected over 2 years.
Because BP screening by community health workers was common to all 4 randomized groups, the cost of screening was not considered in the comparative analysis. However, it was included in estimating the impact of upscaling strategies on the national health budget, and for this it was assumed that the BP monitors would have a useful life of 5 years with no resale value after that.
All costs are reported in US dollars at the 2007 rate. To control for inflation, all costs were inflated to prices in 2007, with the use of the gross domestic product deflator of 7.7% for Pakistan.14 The mean exchange rate for the year was used to convert costs from Pakistan rupees into US dollars. To adjust for time preference, all costs and effects were discounted; in accordance with the International Society for Pharmacoeconomics and Outcomes Research guidelines, an annual discount rate of 5% over 2 years was used.15,16
The primary outcome measure for the study was the change in systolic BP from baseline to the last follow-up visit. The secondary outcome measure was the proportion of participants with controlled BP (<140 mm Hg for systolic BP and <90 mm Hg for diastolic BP) at the last follow-up visit.
We compared the costs of each randomized intervention to the no-intervention group on an intention-to-treat principle.
ICERs were computed to compare the additional costs and effects of each intervention with the other.12 Uncertainty in the point estimate of the ICERs was investigated with the use of a nonparametric bootstrap with 1000 replications varying the BP effects while costs remained the same.8 The bootstrap was used to estimate 95% CIs around differences in ICERs between randomized groups and to produce scatterplots for the interventions on a cost-effectiveness plane (Figure).17,18
Cost per CVD Disability-Adjusted Life-Year Averted
To facilitate comparison with other programs for competing priorities, the most cost-effective of the alternatives considered was expressed in terms of the cost per disability-adjusted life-year (DALY) averted. The DALY is a generic measure of the burden of disease that combines healthy life-years lost because of premature mortality with those lost as a result of disability.19 The metric thus enables assessment of burden of disease and is helpful for policymakers for resource allocation during health planning.
To assess the impact on the national health budget, the cost per participant of intervention was translated into per capita cost for the population of Pakistan from the policymakers' perspective. In addition, the per capita cost per CVD DALY averted analysis was performed from both the policymakers' and the societal perspectives. Because the relationship between the fall in BP and the impact on CVD events is linear and well defined, a reduction of 5 mm Hg in BP was assumed to lead to 20% reduction in CVD DALYs.20–22 The cost of 1 CVD DALY averted was computed for an annual burden of 3 176 000 DALYs from CVD for Pakistan, as observed in the Global Burden of Disease Study 2004.23
We undertook a number of sensitivity analyses to assess the impact of uncertainty on the estimates of cost-effectiveness. These included different discount rates of costs and values of systolic BP effectiveness, exclusion of productivity losses, and additional cost inputs, including lifestyle factors such as smoking, expense related to meat consumption, productivity loss of caregiver's time while chaperoning GP visits, and exclusion of lifestyle-related costs (ie, fruit and vegetables). Probabilistic sensitivity analysis with the use of Bayesian principles was conducted to assess simultaneous changes in all patient level variables involved in the costs and main effects. Monte Carlo simulation was performed to determine the mean costs, effects on BP, and ICERs among the treatment groups. We also computed ICERs for the primary outcome incrementally to compare the least costly with the next more costly intervention.24
From the societal perspective, the incremental cost per CVD DALY averted was also computed on the basis of incremental cost estimates from the simulated models. In addition, CVD DALYs averted were computed for declining persistence of effect despite continued intervention assuming a reduction of 1% annually, thus ranging from 20% to 10% or a 50% reduction in benefit.
Finally, we also performed an additional sensitivity analysis to estimate the cost-effectiveness of the interventions in a high-income country like the United States, assuming similar effectiveness on BP with application of US cost estimates. The latter was done by (1) converting all costs in Pakistan rupees to the US international dollar equivalent corresponding to purchasing power parity for the year 2007 (1 US dollar=22.7 Pakistan rupees) and (2) specific replacement of itemized costs in Pakistan with US estimates related to GP consultation fee, personnel and health workers' salaries, medications, and diagnostics, which take into account the higher healthcare prices in the United States.25 The cost of 1 CVD DALY averted was based on the ICER for US cost data and computed for an annual burden of 5 853 000 DALYs from CVD, as observed in the Global Burden of Disease Study 2004.
All authors had full access to the data and take responsibility for the integrity of the data and the accuracy of the data analysis.
Overall, 1341 study participants were randomized: 332 to HHE plus trained GP, 348 to HHE only, 335 to trained GP only, and 326 to no intervention. The baseline characteristics of hypertensive adults in the randomized groups are shown in Table 1. A total of 1044 subjects (78%) completed 2 years of follow-up.
Intervention and Resource Utilization Costs
The annual intervention costs per participant (ie, from the perspective of the policymaker) varied substantially for the intervention groups, with the most expensive being the joint intervention group, which was ≈4 times higher than the GP intervention only group (Table 2).
The expenditures per participant for direct healthcare, including physician consultation, medications, and diagnostics at baseline and follow-up are shown in Table 3. The use and associated cost of antihypertensive medications increased from baseline to follow-up in all groups; this increase was more pronounced in the groups with trained GPs (Table 4). The decrease in expenditure on fruit and vegetables was most marked in the combined HHE plus trained GP group, probably reflecting a shift to low-cost seasonal produce, as advised. However, despite emphasis during GP training that thiazide diuretics be the first-line agent for most hypertensive patients, their use remained low (<3% in all groups).
As reported previously, systolic BP declined in all 4 groups. The decline in systolic BP (adjusted for age, sex, and baseline BP) was significantly more pronounced in the HHE plus trained GP care group (11 mm Hg; P=0.001) compared with the other groups (≈6 mm Hg in each). We also detected a significant interaction in the proportion of patients with controlled BP (P<0.001) between the main effects of GP training and HHE. Thus, a substantially greater proportion of patients (56.9%) achieved controlled BP in the HHE and trained GP group than in the other groups (trained GP only, 29.0%; HHE only, 23.0%; no intervention, 27.3%; P<0.003 for difference among groups). The mean per capita expenditure by respondents on all healthcare over 2 years is shown in Table 5. Although the direct costs for HHE plus trained GP were highest at $189, the reported productivity loss was greatest for the trained GP group. The expenditure on fruits and vegetables was also highest in the latter, which was partly responsible for the overall highest costs at $538 for the trained GP group.
Incremental Cost-Effectiveness Ratios
From a societal perspective, the combined intervention of HHE plus trained GP yielded a bootstrapped ICER of $23 (95% CI, 6–99) per mm Hg reduction in systolic BP compared with no intervention (usual care) (Table 5). When discounted at 5%, the combined intervention of HHE plus trained GP yielded an ICER of $23 (95% CI, 7–101) per mm Hg reduction in systolic BP compared with no intervention (usual care). Whether discounted or undiscounted, the ICERs associated with the single interventions were less cost-effective (Table 5) because their CIs were wide in magnitude and direction, ranging from dominant to positive ICERs. Scatterplots of the bootstrapped ICERs illustrate these results (Figure).
Per Capita Cost of Intervention and Cost per CVD DALY Averted for Pakistan
On the basis of a hypertension prevalence of ≈18% in Pakistani adults aged ≥15 years2 (and 60% of the population is in this age range), the estimated cost of the annual combined intervention of HHE and GP training of $3.99 per participant translates into an annual per capita cost of $0.43 for the Pakistani population of 170 000 000.26 From the policymakers' perspective, the HHE plus GP training intervention was estimated to cost $115 per CVD DALY averted. From a societal perspective, the incremental cost of the combined intervention versus usual care was $1226 per CVD DALY averted. Moreover, the additional cost of screening for BP would be ≈$0.06, and thus the cumulative per capita cost incurred to scale up the combined HHE plus GP intervention and BP screening would be US $0.49.
Sensitivity analysis of the outcome parameter by varying change in systolic BP from the trial during computation of 95% limits of ICER confirmed the cost-effectiveness of HHE plus trained GP over the other interventions. Furthermore, exploration of the implications of simultaneous alteration in costs and effects, application of discount rates of 3% and 10% (as recommended by the International Society for Pharmacoeconomics and Outcomes Research),12 additional and reduced costs, as well as application of US cost estimates all revealed the cost-effectiveness of combined HHE plus trained GP over trained GP, HHE, or no intervention (Table 6). The cost per DALY averted for Pakistan increased from $115 to $230 at the policymaker level and from $1226 to $2451 at the societal level with modeling of declining persistence of cardiovascular benefit from 20% to 10%, respectively (Table 7).
The approach of comparing the least to the next more costly intervention (ie, HHE compared with the combined intervention of HHE plus trained GP) yielded an ICER of $77.8 (95% CI, 19.9–275.8) per mm Hg reduction in BP, which translates into $3600 per CVD DALY saved.
From a societal perspective for the United States, on the basis of the prevalence of hypertension of 24% as observed in the Third National Health and Nutrition Examination Survey in adults aged ≥18 years27 (and ≈80% of the population is in this age range), the estimated cost per DALY was I$5770 for the international purchasing power parity cost replacement and $40 466 per DALY averted for itemized replacement of costs.
We found that the combined intervention of HHE by lay health workers and management by trained GPs was more cost-effective for lowering BP than the use of trained GP, HHE, or no intervention in the communities in Karachi. The combined HHE plus GP group was the most cost-effective compared with other interventions, was associated with the bootstrapped ICER of $23 (95% CI, 6–99) per mm Hg reduction in systolic BP compared with usual care, and remained so in 97.7% of 1000 bootstrapped replications. According to the US Panel on Cost-Effectiveness in Health and Medicine, there are no absolute standards for accepting an intervention as cost-effective or not cost-effective on the basis of cost-effectiveness ratios.28 However, the ICER offers a comparative estimate relative to the next best alternative and is therefore more informative for decision making.
Our analyses indicate that from the policymakers' perspective, the combined HHE and trained GP intervention was the most costly (annual cost per participant of $3.99) of the 3 interventions (Table 2). However, the combined program was also the most effective. On the other hand, the HHE only intervention was costly (annual cost per participant of $3.34) and less effective compared with no intervention, whereas the trained GP only intervention had lower costs (annual cost per participant of $0.65) but lower effects. On the other hand, from a societal perspective, the incremental costs relative to usual care were lowest for HHE, although there was no difference in BP levels compared with usual care (Figure). The trained GP group had high costs and no difference in benefit. However, the combined HHE and trained GP intervention had higher costs but also produced a greater benefit than usual care and thus remained the most cost-effective intervention.
Current prevention strategies promoted by the World Health Organization focus on combination drug treatment (low-dose antihypertensives, statins, and aspirin) to manage patients' overall cardiovascular risk profile, which is considered cost-effective for most low- and middle-income countries.14 Although such an approach is attractive, the use of multiple drugs is more expensive, and combined formulations are not yet available. Moreover, the use of risk charts and the clinical assessment required are more complicated than taking a BP measurement. A systematic review of the use of risk charts did not show any strong evidence of improvements in care or risk factor outcomes.29
We utilized the existing healthcare infrastructure in Pakistan to deliver the intervention, hence ensuring logistical feasibility. The community GPs trained during the study were mostly private contractors who continued to provide care on their usual fee-for-service model. Consistent with the pattern of out-of-pocket coverage for medications in Indo-Asia, antihypertensive drugs were also primarily bought by the patients. The door-to-door service of HHE replicated the existing publically funded Lady Health Workers Program of Pakistan in terms of credentials, frequency of visits, and duty hours of the home educators. The Lady Health Workers Program of Pakistan has been implemented for ≈2 decades and provides immunization and basic maternal and preventive child care services.30 The synergistic benefit of HHE and GP training on BP lowering in our study was probably due to mutual reinforcement of healthcare messages.6 Thus, we show that modest investment in strengthening the existing private and public health sectors for BP control can lead to substantial improvement in patient outcomes from a societal perspective. Moreover, the demonstration of success in a largely private physician–dominated healthcare infrastructure suggests that the observed benefit is likely to be enhanced further in the long term by reduction in market failure in the prevention of chronic disease.31
Our results indicate that the majority (>60%) of direct healthcare costs in hypertensive subjects was spent on medications. The proportional cost of medications became even more substantial after 2 years in the 2 groups receiving care from trained GPs (Table 4). The subjects in these groups were also more likely to be receiving antihypertensive agents, perhaps reflecting the effectiveness of the update in management guidelines that underscored the value of appropriate use of antihypertensive agents (Table 4). These findings are supported by a nested study in our population linking GP training with better adherence to antihypertensive medications, which was also linked with improved BP control.32 Additional efforts to overcome barriers to thiazide diuretics are likely to further enhance the economic efficiency of the intervention, as indicated by our results in which overall costs were reduced by >50% with an assumption that these agents were used as first-line antihypertensive agents by patients assigned to trained GPs (Table 7).
The combination of low cost and effectiveness in achieving target BP with the HHE plus trained GP program compares favorably with the results for a similar program deemed cost-effective in the US state of Georgia, in which BP control rates of 68% were achieved with a per capita expenditure of $7.80.33 Although outcomes data have not been reported, a train-the-trainers intervention for BP control costing the same amount has also been implemented successfully across Kyrgyzstan, a lower-middle-income country.
The estimated annual per capita combined intervention cost of $0.43 (or $0.49 inclusive of BP screening) is ≈10% of the current national budgetary allocation to health ($700 million) in Pakistan and only 14% of the current $2.97 per capita spending on maternal and child health programs.26 Moreover, even this cost will be offset somewhat when the program is implemented with the existing Lady Health Workers Program of Pakistan because considerable resource sharing is expected. The per capita gross domestic product of Pakistan is ≈$881 (World Bank estimate for 2007), and the cost per CVD DALY saved from a societal perspective of the combined HHE plus trained GP was $1226 per DALY saved.
According to the World Health Organization, an intervention that saves 1 DALY for <3 times the gross domestic product per capita is considered cost-effective, whereas one that saves 1 DALY for <1 times the gross domestic product per capita is considered very cost-effective.34 These recommendations are consistent with <$1000 per CVD DALYS saved being categorized as highly cost-effective for low-income countries by the Disease Control Priorities Project.35 Moreover, all of the sensitivity analyses indicate that the estimates associated with the combined intervention fall within the range qualifying it to be cost-effective. Furthermore, the $115 per DALY saved with the combined intervention from the policymakers' perspective is comparable to the existing maternal and neonatal care programs in South Asia costing $127 to $394 per DALY averted.8 We believe that our findings have significant public health implications for a substantial proportion of the world's population in Indochina, Africa, and countries where the prevalence of hypertension is high, the mixed public/private healthcare system is comparable in terms of upscaling strategies with the use of a nonphysician workforce and training of existing healthcare providers to achieve a similar effect, and a significant share of the healthcare costs is out of pocket.23,36,37 Thus, the combined strategy of GP training plus HHE intervention could potentially be an effective and affordable intervention for many low-income communities worldwide.28,38
Our analysis has potential limitations. Most studies of cost-effectiveness use the metric of disability or quality-adjusted life-years based on deaths and disabilities from myocardial infarctions and strokes. However, the follow-up duration in COBRA was short because it was not powered to assess differences in these hard outcomes. Instead, the primary measure of effectiveness was determined by reduction in BP, an acceptable outcome measure for cost-effectiveness studies39,40 that is well documented to translate into reduction in cardiovascular morbidity and mortality.22,41 Second, we did not take into account any cost incurred during hospitalizations of subjects in the 4 groups. However, the number of hospitalizations was too few to make a significant difference in the results (<1% of subjects). Nevertheless, a larger study for a longer duration is likely to show an even greater benefit of the combined HHE plus trained GP intervention on potential relief from the financial burden of catastrophic illness due to acute cardiovascular events, which often perpetuates the cycle of poverty in low-income countries.42 Third, our study was conducted in a developing country setting, and hence generalizability to high-income settings with greater opportunities for physician education and public awareness remains unknown.43 Furthermore, the cost differentials, especially those related to healthcare, would be limited. However, sensitivity analyses that assumed similar benefit and that replaced costs incurred in Pakistan with those estimated for the US setting for comparable services in which international purchasing power parity is used (I$5770 per CVD DALY averted) as well as after itemized replacements with rather excessive healthcare costs in the United States ($40 644 per CVD DALY averted) were both within 1 per capita gross domestic product of the United States (World Bank estimate $46 627 for 2007) and hence revealed consistent findings. Thus, the combined intervention of HHE by lay health workers plus trained GPs is likely to be cost-effective in industrialized countries with high human resource costs as well. Finally, ≈22% of subjects were lost to follow-up. However, they were balanced among the randomized groups.6 Moreover, we analyzed both costs and effects on an intention-to-treat principle. The strengths of our study are the use of empirical cost and effectiveness data and the consistency of results over a range of sensitivity analyses, including those not accounting for productivity losses, as well as inclusion of additional cost inputs that further enhanced the benefit of the combined HHE plus trained GP intervention by lowering ICER to 17 (95% CI, 5–75; Table 6) and after assumption of a substantial reduction in effect, although evidence from a meta-analysis of clinical trials suggests persistence of effect.44 Furthermore, our study was built on the existing health system that supports the feasibility, acceptability, and high likelihood of wide implementation and sustainability if the intervention is scaled up. Thus, we believe that our findings are robust and of high validity.
In conclusion, the present analyses show that the combined intervention of HHE plus trained GP in the management of hypertension is potentially affordable and significantly more cost-effective than usual care or either strategy alone in the communities of Karachi, Pakistan. These results provide valuable guidance to policymakers for upscaling the combined cost-effective intervention now as well as conducting further in-depth research on improving CVD outcomes in Pakistan and other resource-challenged countries with a rising burden of high BP that demands immediate public health attention.45
Sources of Funding
The study was financially supported by a research award (070854/Z/03/Z) from the Wellcome Trust, UK. The design, conduct, analysis, interpretation, and presentation of the data were the responsibility of the authors, with no involvement from the funder.
We would like to thank all members of the Hypertension Research Group. We would also like to acknowledge Mark J. Sculpher, Professor of Economics at the University of York, York, UK, for reviewing the article and providing critical comments.
- Received April 23, 2011.
- Accepted August 8, 2011.
- © 2011 American Heart Association, Inc.
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- Riley LM,
- Ezzati M
High blood pressure (BP) contributes the greatest attributable risk to mortality worldwide. However, evidence on economically efficient strategies to lower 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 compared with usual care: (1) combined home health education (HHE) by lay health workers plus management by trained general practitioners (GPs); (2) HHE only; and (3) trained GPs only. The HHE intervention was modeled on the existing Lady Health Workers Program in Pakistan and provided education on healthy diet, physical activity, and tobacco cessation in the home setting at 3-month intervals. GP training was an annual 1-day session on optimal hypertension management. Total costs and effects 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. We found that combined HHE plus GP intervention led to the most BP reduction for the cost (incremental cost-effectiveness ratio of $23 per mm Hg reduction in systolic BP compared with usual care) and remained so in 97.7% of 1000 bootstrapped replications. The estimated cost of the combined intervention was $115 per disability-adjusted life-year averted from the policymakers' perspective and $1226 per disability-adjusted life-year averted from the societal perspective; $0.43 per capita population per year would be needed to scale up the intervention in Pakistan. Thus, the combined intervention of GP training plus HHE intervention could potentially be an effective and affordable strategy for many low- and middle-income countries worldwide that are urgently in need of efforts to prevent and control hypertension.