Intervention strategies to reduce the burden of non-communicable diseases in Mexico: cost effectiveness analysis

Overview

The figure⇓ summarises information on costs, population health effects, and cost effectiveness (compared with the null) for all interventions. Across the 101 interventions examined in this study, the average yearly costs at the population level ranged from ≤$Int1m (for cataract surgeries and some elements of cervical cancer treatment) to >$Int1bn (for high coverage of treatment for hypercholesterolaemia or aggressive management of absolute cardiovascular risks). Comparing the total annualised population health benefits across interventions, we again observed a wide range of outcomes, from <1000 DALYs averted a year (for some components of cancer treatments or aspirin for acute ischaemic stroke) to >300 000 DALYs averted a year (for aggressive combination of interventions to deal with alcohol use, which was the leading risk factor for the burden of disease in Mexico in 2004,6 and cardiovascular risks).

Costs, population health effects, and cost effectiveness of 101 intervention strategies in Mexico, by intervention package

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In the figure⇑, with both axes displayed on a log scale, diagonal lines moving from the lower left to the upper right direction are cost effectiveness isoquants, which means that any point on the same line as another point has the same average cost effectiveness ratio compared with the null. Thus, these figures offer an easy graphical display of broad bands of cost effectiveness across interventions. The interventions in this study spanned a wide range of average cost effectiveness ratios, differing by more than three orders of magnitude between the lowest and highest ratios. At the low end, some interventions cost <$Int100 per DALY averted, such as taxation interventions for alcohol. At the high end, we identified interventions that cost >$Int100 000 per DALY, such as high intensity treatment for chronic obstructive pulmonary disease or aspirin for acute ischaemic stroke.

Comparison across intervention packages

The interventions in this analysis pertained to three different packages of interventions covered by the health reform scheme: community and public health interventions; low and medium complexity clinical interventions; and high complexity clinical interventions. The reform specified that each of these categories of interventions should be financed from a separate fund. The figure⇑ distinguishes interventions falling into these three broad categories. The community and public health interventions included non-personal interventions for alcohol use, tobacco use, and cardiovascular risks; and screening for breast cancer and cervical cancer. Overall, the community and public health interventions tended to have high benefits and medium level overall costs and tended to have lower cost effectiveness ratios than many of the interventions in the other two categories. Even within the community and public health interventions, however, there was more than a 200-fold difference between the highest and lowest cost effectiveness ratios.

Low and medium complexity healthcare interventions included personal services for alcohol use, tobacco use, and cardiovascular disease prevention; treatment for chronic obstructive pulmonary disease; interventions for depression; cataract surgery; and secondary prevention for diabetes. High complexity healthcare interventions included treatment for ischaemic heart disease, stroke, and congestive heart failure and treatment for breast cancer and cervical cancer. In terms of total costs and total benefits, the high complexity interventions tended to have lower totals than the low and medium complexity interventions, mainly because the target populations for these services were smaller on average. In terms of cost effectiveness ratios, on the other hand, there was little discernable difference between the two groups of interventions. Cost effectiveness ratios both for low and medium complexity interventions and for high complexity interventions spanned ranges of more than three orders of magnitude.

Results by disease cluster

Full results on the yearly costs, population effects, and cost effectiveness ratios for all 101 interventions are provided in the appendix table on bmj.com. Here we summarise the costs, effects, and average cost effectiveness results by intervention cluster. The average cost effectiveness ratio can be understood as the cost effectiveness of an intervention compared with a null scenario (no intervention). When we compare mutually exclusive interventions within a cluster, we also describe incremental cost effectiveness ratios, which were based on the net costs and net effects of an intervention compared with the next most effective, non-dominated intervention.

Depression—We evaluated four main interventions for the treatment of depression—older antidepressant drugs (tricyclic antidepressants), newer antidepressants (selective serotonin reuptake inhibitors), psychotherapy, and proactive case management—as well as various combinations of these interventions. We found that proactive care combined with older or newer antidepressants had the biggest impact on population health, averting almost double the number of DALYs averted by psychotherapy or antidepressants alone. All examined strategies had average cost effectiveness ratios below the per capita GDP in Mexico for each DALY averted, making them cost effective by international standards. Regarding all interventions and combinations as mutually exclusive competing choices, we found that two interventions dominated all others: newer antidepressants compared with the status quo, which had an incremental cost effectiveness ratio <$Int1500 per DALY averted, and the combination of newer antidepressants with psychotherapy and proactive management, which had an incremental cost effectiveness ratio around $Int3400 per DALY averted.

Heavy alcohol use—We evaluated five main types of interventions for heavy alcohol use (including taxation at various levels, random roadside breath testing, brief advice in primary healthcare, reduced access at retail sales locations, and a comprehensive advertising ban) as well as various combinations of these interventions. We found that taxation interventions produced the highest overall population health benefits and were also among the lowest cost interventions in this group. The taxation interventions, along with interventions to reduce retail access and limit advertising, all had highly attractive cost effectiveness ratios compared with doing nothing (<$Int350 per DALY averted, or <$Int100 per DALY averted in the case of the tax interventions). Even the interventions with the highest cost effectiveness ratios in this cluster (breath testing and brief physician advice) had costs per DALY below the per capita GDP of Mexico, making them highly cost effective by international standards. Considering the incremental costs and effects of interventions treated as competing choices, we found that an aggressive tax increase had an incremental cost effectiveness ratio of only $Int72 per DALY averted compared with the null (and dominated the status quo); adding a ban on advertising yielded an incremental cost effectiveness ratio of $Int320 per DALY averted compared with only the tax increase. Combining the tax increase, advertising ban, brief advice, and reduced access had an incremental cost effectiveness ratio around $Int1800, and adding roadside breath testing produced an incremental cost effectiveness ratio around I$10 900, which is close to the GDP per capita in Mexico.

Tobacco use—We evaluated four main types of interventions for tobacco use (taxation at different levels, clean indoor air law enforcement, nicotine replacement therapy, and a comprehensive advertising ban) and several combinations of these interventions. As with alcohol, we found that taxation interventions were effective in terms of population health benefits, inexpensive compared with other interventions, and highly cost effective. A comprehensive advertising ban and clean air law enforcement would also be characterised as highly cost effective using the benchmark of averting each DALY at a cost of less than Mexico’s GDP per capita, whereas nicotine replacement therapy exceeded the threshold of three times GDP per capita per DALY averted, which made this intervention not cost effective according to international standards. In the incremental analysis, increased taxation had an incremental cost effectiveness ratio of around $Int140 per DALY averted compared with the status quo; adding a ban on advertising produced an incremental cost effectiveness ratio of $Int2800.

Cataract —The only effective treatment for cataracts is cataract surgery to remove the opacified lens. We evaluated two different types of cataract surgery: conventional extracapsular cataract extraction and phacoemulsification. Both procedures were assessed at three target coverage levels (50%, 80%, and 95%) for a total of six separate intervention analyses. Both surgeries, at any coverage level, were found to have average cost effectiveness ratios below $Int100, making them among the most cost effective of all interventions examined across different clusters. In terms of comparisons between the different types, phacoemulsification dominated extracapsular cataract extraction at any given coverage level. At a coverage of 95%, phacoemulsification had an incremental cost effectiveness ratio of $Int43 per DALY averted compared with extracapsular cataract extraction at 95% coverage.

Breast cancer—We evaluated treatment of breast cancer, including a disaggregated analysis of costs and effects of treatment at different stages, as well as a strategy of treatment plus routine population screening according to the Mexican norm at the time of analysis. Considering the benefits of treatment, we found that treating tumours at earlier stages contributed greater health benefits overall than treatment at later stages and that population screening, while costly, would provide substantial additional benefits over clinical detection. The cost effectiveness ratios for breast cancer treatment fell below Mexico’s per capita GDP per DALY averted, making treatment highly cost effective. Adding screening to treatment according to the norm at the time of analysis had an incremental cost effectiveness ratio of $Int22 000 (that is, falling between one and three times GDP per capita for each DALY averted), implying that screening would be potentially cost effective, but not highly cost effective according to international benchmarks.

Cervical cancer—Analyses for cervical cancer, similarly to the breast cancer analyses, evaluated strategies for treatment without screening or treatment combined with routine population screening according to the Mexican norm. The overall findings for cervical cancer interventions mirrored those for breast cancer, with treatment at earlier stages (including the precancerous stage of cervical intraepithelial neoplasia, grade II or III) contributing greater benefits than treatment at later stages. Even the relatively more costly and less effective treatments of later stages of cancer were found to be cost effective components of the overall treatment strategy, based on falling below the threshold of per capita GDP for each DALY averted. For cervical cancer, screening was among the most efficient strategies, increasing overall benefits more than 10-fold. The incremental cost effectiveness ratio for screening and treatment, compared with treatment without screening, was around $Int5600 per DALY averted, which implied that screening would be highly cost effective.

Chronic obstructive pulmonary disease—Current interventions for chronic obstructive pulmonary disease (COPD) are aimed at slowing the progression of the decline in lung function associated with the disease. We evaluated five main interventions: intensive smoking cessation programme for current smokers with a diagnosis of COPD; influenza vaccination of COPD patients aged ≥65; inhaled bronchodilator for those with mild COPD; inhaled bronchodilator and corticosteroid for those with moderate to severe COPD; long term oxygen treatment (in addition to bronchodilator and corticosteroid) for those with severe COPD; and treatment of severe COPD exacerbations. We found that treatment of severe exacerbations associated with COPD averted the smallest number of DALYs, followed by long term oxygen treatment, inhaled bronchodilator for mild COPD, and then an inhaled bronchodilator plus inhaled corticosteroid for moderate to severe COPD. Influenza vaccine for people with COPD and an intensive smoking cessation programme for those diagnosed with COPD had the largest benefits in terms of DALYs averted and were less expensive than interventions directed solely at patients with later stages of disease. These were also the only two interventions with average cost effectiveness ratios below three times GDP per capita in Mexico (both having ratios between $Int2500 and $Int5000). Given the focus of the different interventions on different target populations, we did not conduct an incremental analysis treating the interventions as competing choices.

Cardiovascular disease—We evaluated a wide range of interventions for primary prevention, treatment, and secondary prevention for cardiovascular disease. Prevention interventions included non-personal interventions involving health education through mass media programmes, legislation or voluntary agreements with the food industry, as well as personal health service interventions including detection and treatment of high risk individuals based on blood pressure, serum cholesterol, and absolute risk thresholds. The absolute risk approach estimates the combined risk of a cardiovascular event over the next decade above a given threshold, based on relative risk estimates of modelled risk factors. We also assessed 30 single interventions and combinations of interventions for treatment and secondary prevention relating to acute myocardial infarction, stroke, and congestive heart failure. All primary prevention interventions were found to be highly cost effective according to international benchmarks. Among population level (non-personal) interventions, those aimed at reducing blood pressure and cholesterol, and salt reduction through legislation, had the lowest costs per DALY. Individual primary prevention interventions resulted in much greater effectiveness, although they were more costly per unit of health benefit than the population-wide strategies. In incremental analyses, population salt reduction, a comprehensive population combination intervention, and absolute risk threshold approaches dominated all individual strategies focusing on either hypertension or cholesterol alone. The most aggressive strategy based on absolute risk thresholds, focusing on all patients with risks above 5%, was the most effective but at an incremental cost effectiveness ratio that was well above the benchmark of three times GDP per capita. All treatment interventions for myocardial infarction were found to be highly cost effective or cost effective in comparing average cost effectiveness ratios to GDP based benchmarks, with cardiac rehabilitation producing the most attractive cost effectiveness ratios because of the relatively low cost of this intervention combined with moderate population level health effects. For stroke, only post-acute stroke interventions were found to be highly cost effective, while interventions targeting the acute period resulted in low health gains at significantly higher costs. All heart failure interventions were highly cost effective, with diuretics being the most cost effective in the group. Because the set of interventions were not mutually exclusive, we have not reported on a full set of incremental comparisons for the cluster of interventions relating to cardiovascular disease.

Diabetes—We evaluated four main interventions for secondary prevention of type 2 diabetes: blood pressure control, lipid control, and conventional or intensive glycaemic control. With a high overall prevalence of diabetes in Mexico, the largest population benefits would be realised through glycaemic control. The average cost effectiveness ratios for conventional and intensive glycaemic control were about $Int12 500 and $Int13 600 per DALY averted, respectively, implying that glycaemic control is potentially cost effective at less than two times per capita GDP. Considering the incremental cost effectiveness of intensive compared with conventional glycaemic control, the more intensive strategy had an incremental ratio of around $Int16 900. Lipid control for patients with diabetes would produce a much smaller overall population benefit, but at an average cost effectiveness ratio similar to that for glycaemic control. Blood pressure control would produce an overall benefit between that for lipid control and that for glycaemic control. The cost effectiveness ratio for blood pressure control, however, was considerably lower than those for the other two interventions. At around $Int8500 per DALY averted, blood pressure control would be classified as highly cost effective according to standard international benchmarks.

Sensitivity of results to choice of health metric

In our base case analysis, we have focused on measuring population health effects of interventions using DALYs that reflect differential age weights, such that health outcomes experienced during young adulthood are weighted more heavily than those during childhood or older adult years. We examined the sensitivity of results to the inclusion of age weights by recalculating all health effects and cost effectiveness ratios with equal weights at all ages. The appendix figure on bmj.com compares the yearly population health effects for all 101 intervention strategies under scenarios with and without age weights, indicating a high degree of consistency. Examining the average cost effectiveness ratios in the scenario without age weighting (shown for all interventions in the appendix table on bmj.com), we found that only two interventions moved from one broad category (that is, highly cost effective, potentially cost effective, not cost effective) to another. These were nicotine replacement therapy, which shifted from not cost effective to potentially cost effective with the removal of age weights, and angiotensin converting enzyme (ACE) inhibitors for acute myocardial infarction, which shifted from potentially cost effective to highly cost effective; both of these shifts were based on relatively small changes in the ratios. Overall, this analysis indicated that the results in general were highly robust to the choice of age weighted DALYs averted as the primary indicator of population health benefits.