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The Effects of Conditional Cash Transfers on BMI and Blood Pressure in Adults

Development Challenge

Undernutrition has long been a fundamental issue in low-resource settings. While it remains a problem today, many countries in the developing world have seen simultaneous, paradoxical rises in rates of obesity and non-communicable diseases, such as hypertension [1][2]. Conditional cash transfer (CCT) programs are often lauded for their success in alleviating poverty and improving child health and education outcomes.  However, there is no evidence on the effect of CCTs on adult health.

Context

Mexico’s 2006 National Nutrition and Health Survey found that 67 percent of males and 72 percent of females were overweight or obese.  Diabetes and hypertension rates were also high [3]. Previous research of low-income adults in Mexico has linked higher socioeconomic status to higher rates of obesity [4].

Oportunidades (originally Progresa), a Mexican conditional cash transfer program, launched in 1997 to eliminate extreme poverty and improve health and education outcomes. The cash transfers, conditional on receiving preventative medical services or school attendance, successfully improved child health and development outcomes; however, the effects on adult health outcomes remained unstudied.

Evaluation Strategy

Oportunidades was randomly rolled out across 506 communities in seven states. In 1997 there were 320 treatment and 186 comparison communities. After 18 months the 186 comparison communities were later enrolled in the program. The study used a stepped-wedge design to incorporate the comparison communities into treatment. The researchers collected anthropometric measures in 2003 to merge with Oportunidades’ administrative records. The primary health outcomes measured included body mass index (BMI), diastolic blood pressure (DBP), systolic blood pressure (SBP), and current uncontrolled hypertension [5]. Self-reported distance able to walk – a proxy of self-reported health – was also measured.  

Due to the absence of early anthropomorphic data, the researchers did not compare beneficiaries to non-beneficiaries.  Rather, researchers exploited the magnitude of the cash transfers received to statistically identify effects on adult health outcomes.

Results and Policy Implications

Researchers found that participation in Oportunidades was associated with higher BMI, hypertension, and blood pressure. Yet, greater exposure to the program’s requirements – preventative healthcare, regular checkups and attendance at educational seminars – were associated with better health outcomes. Oportunidades participants had a mean BMI above 25, the cutoff for being considered overweight.  Doubling the cumulative cash transfer amount was also highly correlated with obesity and high blood pressure.

In contrast, however, researchers detected no significant associations between CCTs and SBP.  In fact, an additional 18 months of CCTs was associated with an improved ability to walk without tiring. Increased exposure to the program’s conditionalities was associated with a lower prevalence of obesity and hypertension among women, although the results were not statistically significant.

There are several possible explanations.  Increased income leads to greater availability of high fat and energy dense foods, which in turn, contributes to obesity and high blood pressure.  Indeed, studies have documented increased access to high fat food in Mexico [6][7], a finding which supports this hypothesis. Though these results are suggestive of negative effects in adults, they are inconclusive, and the study faces several data limitations.  Notwithstanding, the results suggest that while CCTs may be an important poverty alleviation tool, programs may need to address possible adverse health outcomes for adults.

[1] Popkin, B. M. (2001). The nutrition transition and obesity in the developing world. The Journal of nutrition131(3), 871S-873S.

[2] Rivera JA, Barquera S, Campirano F, Campos I, Safdie M, Tovar V. Epidemiological and nutritional transition in Mexico: rapid increase of non-communicable chronic diseases and obesity. Public Health Nutr. 2002;5:113–22.

[3] Gonzalez Villalpando C, Stern MP, Arredondo Perez B, Valdez R, Mitchell B, Haffner S. Prevalence and detection of hypertension in Mexico. Arch Med Res. 1994;25:347–53.

[4] Fernald LCH.  Socioeconomic status and body mass index in low-income Mexican adults.  Soc Sci Med.  2007;84:274-88.

[5] Current uncontrolled hypertension was defined as DBP ≥ 90 mm Hg or SBP ≥ 140 mm Hg

[6] Bermudez OI, Tucker KL. Trends in dietary patterns of Latin American populations. Cad Saude Publica. 2003;19 Suppl 1:S87–99.

[7] Kain J, Vio F, Albala C. Obesity trends and determinant factors in Latin America. Cad Saude Publica. 2003;19 Suppl 1:S77–86.

Photo Credit: Pedestrian Mall, Mexico City. By Design for Health, via Flickr