Using the CHD Policy Model, a Markov-style computer model of CHD and stroke, we estimated that the proportion of CHD and stroke attributable to SBP, active and passive smoking, LDL cholesterol, HDL cholesterol, diabetes and BMI were in most cases similar in Argentina and the United States. CHD attributable to elevated BMI was considerably more in the U.S. compared with Argentina (>10 percentage points higher in men and women). Adjusting blood pressure relative risks to reflect a higher propotion of hemorrhagic stroke in Argentina led to a >12 percentage point higher proportion of total stroke attributed to elevated systolic blood pressure.
The higher mean SBP and higher proportion of cardiovascular disease attributed to elevated blood pressure in Argentine men may be due to the 10% rate of hypertension control in Argentina[30
] compared with >34% in U.S. men,[31
] and lack of the same difference in women due to low rates of hypertension control in U.S. women ≥60 years old.[32
] National blood pressure surveys and treatment guidelines have achieved a measurable degree of success in the U.S.[33
] Argentina implemented a national hypertension control program based on World Health Organization (WHO) guidelines in 2008–2009, but the effect of this program on blood pressure treatment and control rates has yet to be measured.
Apparent similarities in the proportion of cardiovascular disease attributable to elevated SBP, dyslipidemia, and diabetes in Argentine and U.S. women may mask underlying differences. The U.S. has a high prevalence of obesity compared with nations like Argentina, presumably due to both higher caloric intake and less physical activity,[34
] though obesity prevalence may be rising in Argentina among lower income and education status groups.[12
] The much higher proportion of cardiovascular disease (particularly CHD) attributable to elevated BMI in the U.S. suggests that a large proportion of cardiovascular disease is associated with “secondary” high BP, dyslipidemia and diabetes (downstream of elevated BMI), while in Argentina BMI is lower on average and “primary” high BP, dyslipidemia and diabetes are more common. The approach of this analysis was to shift risk factor distributions toward a lower risk level, but it did not account for differences in risk factor distributions in the two nations. For example, while mean SBP and BMI were similar (), SBP ≥140 mm Hg is more prevalent in Argentine men aged 35–64 years (22.5% Argentina and 12.9% U.S.), and obesity (BMI ≥30 kg/m2
) more prevalent in U.S. men of the same ages (31.7% U.S. and 16.0% Argentina).
CARMELA reported that prevalence of hypertension (29%), elevated total cholesterol (≥240 mg/dl, 19%), and active smoking (39%) in Buenos Aires were among the highest of the seven Latin American cities sampled, while it was in the ‘middle of the pack’ regarding obesity (BMI ≥30 kg/m2
, 19.7%) and diabetes (6.2%).[2
] In the U.S., since 1990 active cigartette smoking, high total cholesterol, and hypertension have all declined in prevalence, while prevalence of obesity and diabetes have increased.[35
] National survey data from Argentina indicate that active smoking has declined by an absolute 5% since 1990.[12
] Argentina’s trend trajectories for SBP, LDL and HDL cholesterol, passive smoking, diabetes, and BMI are not known, and will only be known when results from the 2009–2010 National Survey and additional population-based surveys become available. Despite a more constrained ardiovascular disease prevention budget, Argentina has proposed several programs aimed at controllig cardiovascular disease risk factors, such as the “Argentina Saludable” program (http://www.msal.gov.ar/argentina_saludable/
While future risk factor secular trends remain uncertain in Argentina, its cardiovascular disease mortality is lower than in most other Latin American nations and has definitely been declining since 1970.[1
] The explantion for the mortality declines could be favorable trends in risk factors, improved acute care and/or secondary prevention,[37
] or a background of progressive economic development.[38
] Nonetheless, Argentina’s cardiovascular mortality has declined less than mortality due to infectious and maternal/child diseases and noncommunicable diseases now constitute nearly 65% of total deaths.[39
] It is therefore unclear if Argentina is entering an “epidemiologic transition” toward relatively higher cardiovascular disease mortality experienced a century ago in high income nations like the United States[40
] and occurring in other middle income nations,[41
] or if its cardivascular disease mortality trend will be more benign. Our projected age-standardized stroke event rates were higher in Argentina compared with the U.S. and the ratio of stroke to CHD higher, a pattern that appears to be true for most Latin American nations.[28
The proportion of CHD attributable to unfavorable exposures from selected risk factors in CHD Policy Model simulations (approximately 85% of men and 80% of women) compares reasonably well with the overall proportion of MI attributable to risk factors in INTERHEART Latin America study using more and different risk factors (overall proportion explained 86–88%),[26
] though less well with INTERHEART overall (proportion of MI explained 90% in men and 95% in women).[25
] Estimated proportions of CHD and MI attributable to high BP and diabetes were similar to MI attributable risks reported by INTERHEART Latin America for Argentina, but our estimated proportion of MI attributable to smoking in Argentina was considerably smaller ( 10.1% in men and 7.2% in women compared with 42.5% in men and 25.7% in women in INTERHEART Latin America).[26
] Eliminating active smoking in isolation (and not in concert with other risk factors) would bring the proportion of MI attributable to active smoking in Argentina in our analysis to 24% in men and 10% in women. Using only active smoking prevalence, we approximate MI smoking attributable risk to be between 23–37% in men and 12–21% in women in INTERHEART Latin America, depending on assumed number of cigarettes smoked per day.
Approximately half of stroke events remained unexplained by elevated SBP, smoking, or diabetes in our simulations. When we weighted blood pressure relative risks for stroke to reflect a higher proportion of hemorrhagic stroke in Argentina, approximately 30% of total stroke in men and 37% in women remained unexplained by the blood pressure, tobacco smoking, and diabetes. Our stroke analysis was limited by not including universal stroke risk factors not measured in Argentine surveys, such as alcohol intake and atrial fibrillation, additional cardiovascular risk factors common to CHD[25
] and stroke,[42
] or stroke risk factors specific to Argentina (such as Chagas disease).[28
] Our estimates of total stroke attributable to elevated SBP and diabetes are in the range reported by INTERSTROKE.[42
] Relatively lower proportions attributed to smoking are likely mostly a function of overall higher smoking prevalence in INTERSTROKE.
A limitation of this analysis was that active and passive smoking prevalence in Argentina was obtained from a national survey, but other risk factor estimates used for Argentina were from CARMELA, which sampled adults in Buenos Aires city only. Because CARMELA sampled Buenos Aires only, estimates based on CARMELA measurements may not be generalizable to Argentina as a whole. Risk factor means and proportions for U.S. adults are representative of the overall population so this analysis is limited in that U.S. race/ethnic subgroups and urban and rural populations were not analyzed separately.