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Religious involvement has been associated with improved health practices and outcomes; however, no ethnically-diverse community-based study has examined differences in cardiac risk factors, subclinical cardiovascular disease, and cardiovascular disease (CVD) events across levels of religiosity.
We included 5474 White, Black, Hispanic, and Chinese participants who attended Exam 2 of the NHLBI’s MESA study. We compared cross-sectional differences in cardiac risk factors and subclinical CVD, and longitudinal CVD event rates across self-reported levels of religious participation, prayer/meditation, and spirituality. Multivariable-adjusted regression models were fitted to assess associations of measures of religiosity with risk factors, subclinical CVD, and CVD events. MESA participants (52.4% female, mean age 63) with greater levels of religious participation were more likely to be female and black. After adjustment for demographic covariates, participants who attended services daily, compared with never, were significantly more likely to be obese (adjusted odds ratio 1.57, 95% confidence interval [CI] 1.12 – 1.72), but less likely to smoke (adjusted odds ratio 0.39, 95% CI 0.26 – 0.58). Results were similar for those with frequent prayer/meditation or high levels of spirituality. There were no consistent patterns of association observed between measures of religiosity and presence/extent of subclinical CVD at baseline or incident CVD events during longitudinal follow up over 4 years.
Our results do not confirm those of previous studies associating greater religiosity with overall better health risks and status, at least with regard to CVD. There was no reduction in risk for CVD events associated with greater religiosity.
Religious involvement has consistently been associated with improved health practices and outcomes. Longitudinal and cross-sectional studies have found a lower prevalence of smoking1–4 and lower mortality rates1,5,6 among those who attend religious services frequently. Similarly, increased frequency of prayer has been associated with better self-reported health7. Review articles and meta-analyses have corroborated this positive association between religiosity and general health status8–10. Religiosity has also been associated with preventive health care use11.
Studies on religiosity and cardiovascular morbidity and mortality have, likewise, suggested that religious attendance is associated with lower risk6,12–15. However, analyses of the associations between religiosity and obesity have yielded quite different results. Some investigators have found no significant relationship between religiosity and obesity2,16, while others have found an increased prevalence of obesity among the religious3,4,17.
Notable limitations exist in the sampling and methodology of previous studies on religiosity and health. Longitudinal analyses have tended to draw from geographically1,5,12–15 or demographically5,12–15 limited cohorts. Because many studies on religiosity and cardiovascular disease (CVD)-related mortality have drawn from relatively limited cohorts, their conclusions may not be generalizable beyond the geographical regions12–15, age group15, or religion13,14 analyzed therein. One longitudinal analysis6 that associated religiosity with lower all-cause and CVD-related mortality did draw from a nationally representative sample; however, the study did not assess the full spectrum of cardiovascular risk factors and did not measure subclinical atherosclerosis. Another limitation of numerous studies is their measurement of religiosity in a unidimensional manner1,5,6,11,18, despite general agreement that religiosity is in fact a multidimensional construct19–22.
The primary objective of this study was to examine associations between religiosity and health status across the spectrum of cardiovascular health and disease. The multi-center, geographically and ethnically diverse cohort of the Multi-Ethnic Study of Atherosclerosis (MESA) offers an opportunity to expand upon the methodology of previous studies with a larger, more nationally representative sample. In MESA, religiosity was treated multidimensionally; religious participation, frequency of prayer or meditation, and spirituality were examined separately as exposure variables. Likewise, the extensive data available in MESA regarding CVD risk factor burden, presence and extent of subclinical atherosclerosis, and longitudinal CVD event rates provide a unique opportunity for examination of the potentially complex associations between religiosity and CVD.
MESA is a NHLBI-sponsored study designed to examine the prevalence and progression of subclinical atherosclerosis and its progression to overt CVD in a diverse, population-based sample of 6814 men and women aged 45–84 years at baseline who were free of clinical CVD. Study design, recruitment, and procedures have been described in detail previously23. Briefly, at enrollment, the cohort was approximately 40% white, 30% African-American, 20% Hispanic, and 10% Asian (predominantly Chinese). The cohort was recruited from 6 field centers and characterized regarding presence and extent of CVD risk factors and selected measures of subclinical CVD. Participants were then followed longitudinally for re-examination and identification and characterization of CVD events.
Religiosity was measured based on participant responses to a questionnaire given at MESA Exam 2 (which began in 2002). Three dimensions of religiosity were measured: frequency of religious participation, frequency of prayer or meditation, and spirituality. Frequency of participation was determined by responses (never, once or twice a year, monthly, weekly, or daily) to the question: “How often do you attend religious services or otherwise participate in organized religion?” Frequency of prayer or meditation was determined by responses (never, once or twice a year, monthly, weekly, or daily) to the question: “Within your religious or spiritual tradition, how often do you pray or meditate?” Daily spiritual experiences were assessed with 5 items from the Daily Spiritual Experiences Scale (DSES). The DSES is a measure of religiosity and spirituality designed to assess feeling close to God (or the transcendent) and everyday experiences that grow out of that closeness24,25. The 5 DSES items used in MESA were: “I feel God’s presence;” “I find strength and comfort in my religion;” “I feel deep inner peace or harmony;” “I feel God’s love for me, directly or through others;” “I am spiritually touched by the beauty of creation.” Responses to each question were assigned a number (never = 0, once in a while = 1, some days = 2, most days = 3, every day = 4, many times a day = 5), and these numbers were summed to calculate spirituality scores for each participant. Participants were then grouped a priori by spirituality levels: none/never (0–5), low (6–15), moderate (16–20), and high (21–25). Each element within the spirituality scale correlated closely with the overall spirituality score (Cronbach’s alpha varied from 0.86–0.89).
Each of the 6 field centers collected information on anthropometric measures and cardiovascular risk factors, including self-reported history of smoking, hypertension, diabetes, and medication use, during the baseline examination (July 2000 to August 2002) and at Exam 2, concurrent with the questionnaires on religiosity. For the present analysis, risk factor data from Exam 2 were used to assess cross-sectional associations with religiosity. Resting blood pressure was measured using a Dinamap Pro 1000 automated oscillometric sphygmomanometer (Critikin) three times with the participant in a seated position. Hypertension was defined as a systolic blood pressure of ≥140 mmHg, a diastolic blood pressure of ≥90 mmHg, or use of medication prescribed for hypertension. A central laboratory (University of Vermont, Burlington) measured levels of total and HDL cholesterol, triglycerides, and plasma glucose in blood samples obtained following a 12-hour fast, as described previously26. Hypercholesterolemia was defined as a total cholesterol ≥240 mg/dL. Diabetes was defined as a fasting plasma glucose level ≥126 mg/dL or a history of medical treatment for diabetes. The body-mass index was calculated as the weight in kilograms divided by the square of height in meters. Obesity was defined as a body mass index ≥30 kg/m2. Participants were classified as current, former, or never smokers.
Coronary artery calcium (CAC), common carotid IMT (CC-IMT), and LV Mass were obtained at the baseline exam and ABI was obtained at Exam 2. Each of these measures is associated with different manifestations of vascular and myocardial pathology, CAC associates most closely with coronary atherosclerosis and coronary risk, CC-IMT is a measure of atherosclerosis that associates most closely with stroke risk, and LV mass is associated with risk for heart failure and stroke. Each of the six MESA field centers measured the amount of coronary calcium with the use of either an electron-beam CT scanner or a multidetector CT system; scans were then read centrally26. Images of the right and left common carotid (CC) and internal carotid (IC) arteries were captured using high-resolution B-mode ultrasound; images were then read centrally and CC-IMT values were determined according to previously described methods27. End-diastolic left ventricular mass was assessed by 1.5 Tesla MR scanners, then adjusted for body size28. ABI was determined by using a hand-held Doppler instrument with a 5 MHz probe to measure systolic blood pressure at the bilateral brachial, dorsalis pedis, and posterior tibial arteries. Brachial artery pressures were averaged to obtain the ABI denominator; the highest brachial artery pressure was used as the denominator when the two brachial artery pressures differed by 10 mmHg or more. For each lower extremity, the ABI numerator used was the highest pressure from that leg.
At intervals of 9 to 12 months, an interviewer contacted each participant or a family member by telephone to inquire about interim hospital admissions, outpatient diagnoses of CVD, and deaths. To verify self-reported diagnoses, we obtained medical records for participants who had been hospitalized or received an outpatient diagnosis of CVD. Interviews were conducted with the next of kin, and copies of death certificates were requested, for participants who had died of cardiovascular causes outside of the hospital. Two physician members of the MESA Mortality and Morbidity Review Committee independently classified events and assigned incidence dates.
A CVD event was defined as the first occurrence of a CHD event (CHD death, myocardial infarction, or hospitalized unstable angina), stroke, transient ischemic attack, congestive heart failure, or other CVD death. The diagnosis of myocardial infarction was based on a combination of symptoms, electrocardiographic findings, and cardiac biomarker levels26. We used hospital records and family interviews to determine whether deaths were related to CHD. Deaths were considered related to CHD if they occurred within 28 days after a myocardial infarction, if the participant had had chest pain within the 72 hours before death, or if the participant had a history of CHD and there was no known nonatherosclerotic, non-cardiac cause of death. Adjudicators graded hospitalized unstable angina based on their clinical judgment; definite angina required clear and definite documentation of symptoms distinct from myocardial infarction diagnoses.
All analyses were performed using SAS statistical software version 9.2 (SAS Institute, Inc; Cary, NC). Participants were stratified into 5 groups by self-reported levels of religious practice or spirituality: never, 1–2 times per year, monthly, weekly and daily. Baseline characteristics were compared across these groups using general linear models for continuous variables and chi-square tests for categorical variables. For multivariate analyses, the association of religiosity levels and CVD risk factors was examined using linear and logistic regression models with adjustment for demographic information (age, sex, race, education and income), using the frequency level of “never” as the referent group. Similar analyses were performed examining the association of religiosity levels with subclinical CVD with adjustment for demographic covariates as well as CVD risk factor levels. To examine the prospective association between religiosity levels and CVD events, we used Cox proportional hazards regression models. The model was fitted to assess the association of the religiosity measurements and CVD events; it was adjusted for age, sex, race, education and income, as well as blood pressure, total cholesterol, HDL cholesterol, BMI, smoking status, diabetes status, and treatment for hypertension and hyperlipidemia. A two-tailed P<0.05 was considered statistically significant..
We included 5474 White, Black, Hispanic, and Chinese participants who attended Exam 2 of the MESA study and had complete data on the 3 measures of religiosity. Participants were excluded if they did not attend exam 2 of the MESA study. Participants who attended exam 1 but did not attend exam 2 were more likely to be Chinese and Hispanic, and less likely to have attended college, but were generally similar to those participants who attended exam 2 with regard to comorbidities and atherosclerosis burden. Baseline characteristics of the study sample are shown in Tables 1 and and2,2, stratified by the frequency of religious participation and spirituality score, respectively. Results for frequency of prayer or meditation were very similar to those for frequency of religious participation (data not shown). In unadjusted analyses, those who practiced religion more frequently tended to be older, female, and black (Table 1). Systolic blood pressure and BMI were generally higher, while prevalence of smoking was lower, among those who practiced more frequently. Those indicating higher levels of spirituality were more likely to be female and black; they also had higher systolic blood pressure and BMI, but a lower prevalence of smoking (Table 2).
As shown in Table 3, after adjustment for demographic covariates (including age, sex, race, education and income), more frequent religious participants were more likely to be obese and less likely to smoke than those who did not participate at all. Compared with those who never participate in religious activities, each group of religious participants (once or twice a year, monthly, weekly, and daily) was significantly more likely to be obese. Weekly and daily participants had a significantly lower prevalence of smoking than those who never participate. After further adjustment for demographics and smoking status, more frequent religious participants remained significantly more likely to be obese than less frequent participants. The associations of religious participation with obesity and smoking were not attenuated by adjustment for an emotional social support index measured at Exam 1. After adjustment for demographics and risk factor levels, there were no consistent associations observed between frequency of religious participation and prevalence or severity of subclinical CVD (Table 3), as measured by CAC, CC-IMT, LV mass and ABI. Results stratified by frequency of prayer/meditation were similar to those stratified by frequency of religious participation (data not shown).
After adjustment for demographics, those with the highest levels of spirituality were significantly more likely to be obese and less likely to smoke (Table 4). There was also a significantly greater prevalence of obesity and lesser prevalence of smoking among those with low and moderate spirituality, compared with the referent group with the lowest spirituality. After further adjustment for demographics and smoking status, those with greater spirituality remained more likely to be obese. The associations of spirituality with obesity and smoking were not attenuated by adjustment for an emotional social support index measured at Exam 1. There were no statistically significant associations observed between any level of spirituality and prevalence or extent of subclinical CVD.
In a secondary analysis, to assess whether frequency of religious participation or spirituality might have a greater association with obesity or smoking, we adjusted for both dimensions of religiosity simultaneously. For smoking, the magnitude of association was attenuated for both dimensions of religiosity with simultaneous adjustment. For obesity, however, the magnitude of effect and statistical significance for both frequency of participation and spirituality were maintained.
During a mean follow up of 4.1 years, there were 152 incident CVD events, including 9 CVD deaths, 42 myocardial infarctions, 53 hospitalizations for unstable angina, 11 TIAs, 13 cases of congestive heart failure, and 24 strokes. After adjustment for demographics and risk factor levels, none of the dimensions of religiosity appeared to be associated consistently with CVD events (Figure 1). As expected, there were no differences observed between religiosity and specific CVD event types (data not shown) given the low numbers of some types of events.
Our results do not confirm those of previous studies associating greater religiosity with overall better health risks and status1,5–15, at least with regard to CVD. The finding that greater religiosity is associated with obesity has been described previously3,4,17,29, and the negative association found between religiosity and smoking corroborates much of the literature on the topic2–4. We observed fairly similar risks for the presence and extent of subclinical CVD across a broad range of strata in several dimensions of religiosity, including frequency of participation, frequency of prayer/meditation, and spirituality. Likewise, there was no clear reduction in risk for CVD events associated with greater religiosity.
The association found between religiosity and obesity was consistent throughout our study. Each dimension of religiosity was associated to an extent with a greater risk of obesity than no religiosity, with general trends of higher levels of religiosity associating more strongly with obesity than lower levels.
Although some recent studies have found no association between religiosity and obesity2,16, these are countered by our results, as well as by a number of recent studies finding increased prevalence of obesity among more religious individuals3,4,17,29. Geographic and demographic sampling considerations may, in part, account for differences in study findings regarding an association between religiosity and obesity. One study2 finding no association included a sample of medical beneficiaries in five Alabama counties, while the other16 was a sample of only middle-aged and elderly women. By comparison, our study benefited from inclusion of the MESA cohort – a geographically and demographically diverse sample – which may suggest greater external validity for our finding that greater religiosity is associated with a higher risk of obesity.
Various mechanisms may explain the positive association between religiosity and obesity. In their 2006 analysis, Cline and Ferraro posit that one reason for this association is the relative emphasis religious organizations place on avoiding vices like smoking, by comparison to the scant attention paid to avoiding the sin of gluttony29. They also discuss the possibility that religiosity does not lead to obesity, but that obesity may actually lead to religiosity; essentially, religious organizations offer a welcoming environment for those who are obese and seeking protection from social stigma29. Our cross-sectional study design in an older sample cannot rule out this possibility. Another possible reason for the relationship between religiosity and obesity is that the low prevalence of smoking among religious individuals actually causes increased levels of obesity due to the role of smoking as an appetite suppressant. A 2003 study found that positive associations between religiosity and obesity were no longer significant when adjusted for smoking status3. However, our analyses of the relationship between religiosity and obesity that are adjusted for smoking status suggest that the role of smoking as an appetite suppressant does not seem to be the primary explanation for greater obesity among the more religious.
Prior studies have suggested that religious attendance may be associated with lower risk for CVD events. A longitudinal analysis following Alameda County (CA) residents for 31 years found that infrequent (never or less than weekly) religious service attenders had significantly higher rates of death from circulatory disease than frequent religious service attenders12. A retrospective cohort study of Israeli kibbutz members found significantly lower rates of CHD-related mortality among religious males than among secular males13; similarly, another Israeli cohort study found that highly orthodox individuals had lower rates of CHD-related mortality than secular individuals and non-believers14. A prospective cohort study of older adults in New Haven (CT) found that greater worship attendance associated with a lower risk of stroke, although it was determined that health behaviors and pre-existing health status accounted for this association15.
In the present study, we observe that greater religiosity – whether measured as religious practice, frequency of prayer or meditation, or spirituality – is not associated with a lower risk for incident CVD events. Indeed, whereas our power to detect a significant difference in risks for CVD events across strata of religiosity was somewhat limited, the point estimates for association of religiosity with CVD events clearly indicate no evidence for a protective effect of greater religiosity. Considerable effort has been devoted to discussing the role of religiosity in coping with pre-existing illness30–33, but it remains unclear how religiosity relates to the incidence of new illnesses. Additional research regarding religiosity and CVD events would be helpful in determining whether or not our findings are reproducible. Given the relative inconclusiveness of literature on the topic, further investigation of the association between religiosity and CVD events is recommended.
Some limitations of our study should be acknowledged. First, the questions used to assess religiosity in MESA may not adequately capture all aspects of this complex construct. For example, we created a spirituality score to attempt to quantitate the multiple levels of responses to the questions regarding the frequency of spiritual feelings. This metric requires validation in other settings. Nonetheless, the present data do represent an advance over many prior studies that used only unidimensional measures of self-rated religiosity. Another limitation of this analysis is its relatively short period of longitudinal follow-up and resulting low incidence of obesity, smoking, and CVD events; this prevented us from determining temporal causality between religiosity and RFs and limited our power in analyzing the association between religiosity and CVD events. For example, we had 46% power to detect the observed hazards ratio of 1.54 as significant. In order to detect this difference as statistically significant with 80% power, we would have needed a sample size of 4129 participants (rather than the current 1495) in the “daily” and “never” groups. With our current sample, the smallest difference that we would have detected as statistically significant with 80% power was a hazards ratio of 2.45. Finally, the external validity of the study may be limited somewhat because MESA participants represent a volunteer cohort of relatively healthy individuals at inception. Despite such limitations, these data from a well-described multi-ethnic sample provide important insights into potential links between religious attributes and the spectrum of cardiovascular health and disease, and raise interesting questions that merit further exploration.
A variety of behaviors can benefit or harm one’s cardiovascular health, and it has been observed that religious beliefs and practices may influence one’s health behaviors significantly. We sought to determine whether and to what extent different aspects of religiosity might be associated with cardiovascular health. Using a large, ethnically diverse, community-based sample of men and women aged 45 to 84 years who were asymptomatic at baseline, we compared the prevalence of cardiovascular risk factors, the presence and burden of subclinical cardiovascular disease, and the incidence of cardiovascular events across different levels of religiosity. We adjusted for sociodemographic factors in order to ensure that these potential confounders were not responsible for associations found between religion and cardiovascular health. We observed that those who attended services frequently and those who prayed frequently were significantly less likely to smoke than those who never attended services or prayed. Perhaps more surprisingly, we found that frequent service attendees and those who prayed often were significantly more likely to be obese. We did not observe any significant associations between religiosity and presence/extent of subclinical disease or incident cardiovascular events. The consistent and significant association found between religiosity and obesity in this cross-sectional study raises some interesting questions. What is the temporal nature of the association? If being more religious makes one more likely to be obese, why does this occur? Ultimately, this observation should encourage interaction between healthcare providers, public health officials, and the religious community in an effort to improve obesity education and prevention.
This research was supported by contracts N01-HC-95159 through N01-HC-95169 from the National Heart, Lung, and Blood Institute. The authors thank the other investigators, the staff, and the participants of the MESA study for their valuable contributions. A full list of participating MESA investigators and institutions can be found at http://www.mesa-nhlbi.org.
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