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. Author manuscript; available in PMC: 2021 May 1.
Published in final edited form as: Ethn Health. 2018 Mar 7;25(4):598–605. doi: 10.1080/13557858.2018.1439894

Differences in BMI between Mexican and Colombian patients receiving antipsychotics: Results from the International Study of Latinos on Antipsychotics (ISLA).

Bernardo Ng 1,2, Alvaro Camacho 1,3, Katherine Parra 4, Ricardo de la Espriella 4, Victor Rico 5, Severiano Lozano 5, Mirna Troncoso 6, Ruby C Castilla-Puentes 7, Benjamin L Cook 8, Daniel E Jimenez 9
PMCID: PMC6224311  NIHMSID: NIHMS1503848  PMID: 29514516

Abstract

Objective:

The objective of this study is to examine the association of country of residence with body mass index (BMI) between Mexican and Colombian patients exposed to antipsychotics. We hypothesize that there will be a significant association between country of residence and BMI and that Mexican patients will have higher BMI than their Colombian counterparts.

Design:

The International Study of Latinos on Antipsychotics (ISLA) is a multisite, international, cross sectional study of adult Latino patients exposed to antipsychotics in two Latin American Countries (i.e. Mexico and Colombia). Data were collected from a total of 205 patients (149 from Mexico and 56 from Colombia). The sites in Mexico included outpatient clinics in Mexicali, Monterrey and Tijuana. In Colombia, data were collected from outpatient clinics in Bogotá. For this study we included patients attending outpatient psychiatric community clinics that received at least one antipsychotic (new and old generation) for the last 3 months. A linear regression model was used to determine the association of country of residence with BMI for participants exposed to an antipsychotic.

Results:

After controlling for demographics, behaviors, biological and comorbid psychiatric variables, there was a significant difference between Colombia vs. Mexico in the BMI of patients exposed to antipsychotics (β=4.9;p<0.05).

Conclusion:

Our hypotheses were supported. These results suggest that differences in BMI in patients exposed to antipsychotics in Mexico and Colombia may reflect differences in prevalence of overweight/obesity at the population level in the respective countries, and highlights the involvement of other risk factors, which may include genetics.

Keywords: Latino, antipsychotics, obesity, cardiometabolic risk

INTRODUCTION

The Latino population includes diverse groups – Dominicans, Puerto Ricans, Mexicans, Cubans, as well as Central and South Americans. There are sociocultural differences between the groups, including differences in health risks that are likely the result of the known cultural, genetic and socioeconomic heterogeneity of this population (Allison et al. 2008; Daviglus et al., 2012; Roger et al., 2012; Schargrodsky et al., 2008). As such, treating Latinos as a homogeneous group can mask important differences regarding cardiometabolic risk factors such as body mass index (BMI).

Data on the prevalence of cardiometabolic risk factors among Latinos living in the United States (U.S.) is based primarily on Mexican Americans (Roger et al., 2012). However, large epidemiological studies examining the different cardiometabolic risk factors among Latinos different heritage groups have consistently shown that Mexican Americans had a higher mean BMI and increased prevalence of diabetes compared to other Latino groups in the U.S. (Allison et al., 2008 Daviglus et al., 2012; Schargrodsky et al., 2008). Therefore, studies that include Latino groups should not only compare them with other ethnic groups, but also identify within-group differences in health-relevant variables.

Elevated BMI and related medical problems are prevalent among individuals with chronic mental illness (Hellerstein et al., 2007). Those with a chronic mental illness have a nearly four-fold greater risk of developing obesity than people without a previous psychiatric history (Consensus Development, 2004; Henderson, 2005; Saari, 2005). The literature is consistent in that Latinos with a chronic mental illness experience a disproportionate burden of health risk factors compared to non-Latino Whites (74% versus 41%) (Kato et al., 2004). This increased prevalence results from a combination of elevated non-modifiable (ethnicity) and modifiable risk factors (BMI), with new generation or atypical antipsychotic choice emerging as an important modifiable risk factor. Atypical antipsychotics have been associated with significant weight gain, hyperlipidemia, and impaired glucose tolerance (Allison & Casey, 2001).

Despite the known contribution of ethnicity and chronic mental illness to cardiometabolic risk, few studies have identified the effect of atypical antipsychotic exposure with modifiable cardiometabolic risk factors such as BMI in specific ethnic groups (Ananth, Kolli, Gunatilake, & Brown, 2005). A study done by Meyer and colleagues (2009) using genetic data from the Clinical Antipsychotic Trials of Intervention Effectiveness (CATIE) schizophrenia trial suggests that ethnicity may relate to antipsychotic response. This is an area of intense clinical and regulatory interest, given the retrospective data indicating greater risk of antipsychotic metabolic adverse effects (e.g. increased BMI) among Latino patients (Tamayo et al., 2007).

The objective of this study is to examine the association of country of residence with BMI between Mexican and Colombian patients exposed to antipsychotics. Based on prior research (Allison et al., 2008 Daviglus et al., 2012; Schargrodsky et al., 2008), we hypothesize that there will be a significant association between country of residence and BMI and that Mexican patients will have higher BMI than their Colombian counterparts.

METHODS

Participants

The International Study of Latinos on Antipsychotics (ISLA) is a multisite, international, cross sectional study of adult Latino outpatients exposed to antipsychotics in two Latin American Countries (i.e. Mexico and Colombia). Data were collected from a total of 205 patients (149 from Mexico and 56 from Colombia). The sites in Mexico included outpatient clinics in Mexicali, Monterrey and Tijuana. In Colombia, data were collected from outpatient clinics in Bogotá. Our study sample was a convenience sample of patients attending outpatient psychiatric clinics in different cities in Colombia and Mexico. For this study we included patients attending an outpatient psychiatric community clinics that received at least one antipsychotic (new and old generation) for the last 3 months. Patients were included regardless of their diagnosis of a mood, anxiety or a psychotic disorder.

Procedures

Data were collected in 2014. Investigators (experienced clinical psychiatrists) in each site administered a standardized questionnaire that included sociodemographic and clinical measures. Biological information (height, weight, blood pressure, abdominal circumference, serum glucose, total cholesterol, HDL, LDL, triglycerides and HgA1c) were obtained from the patients’ medical records. Participants signed an informed consent prior to answering the questionnaire. The local human research protection program at each site approved the study.

Measures

The primary outcome of this study was BMI. A sociodemographic questionnaire was used to collect information regarding age, gender, level of education, occupation, number of people living in the same household, active medications, number of hospitalizations, type of institution where treatment was rendered (i.e. private, public, academic), number of cigarettes per day, use of alcohol (yes/no), and having a drug problem (yes/no). The MacArthur SES scale was used to collect information on perceived socioeconomic status (Operario, Adler, & Williams, 2004). Also assessed were depression severity using the PHQ-9 (Kroenke, Spitzer, & Williams, 2001) and anxiety severity using the GAD-7 (Spitzer, Kroenke, Williams, & Löwe, 2006); and exercise habits using the Godin Leisure-Time Exercise Questionnaire (Godin & Shepard, 1985). These measures were chosen because of their valid psychometric properties for use with Latino adults (Jamison, Fernald, Burke, & Adler, 2005; Merz, Malcarne, Roesch, Riley, & Sadler, 201; Muñoz-Navarro et al., 2017; Rauh, Hovell, Hofstetter, Sallis, & Gleghorn, 1992).

Statistical Analysis

Continuous variables were checked for normality. They were described by means/standard deviations and categorical variables were described as frequencies/percentages where applicable (Table 1). Both unadjusted and adjusted analyses were performed for all estimates of the difference between country of residence (Colombia vs Mexico-ref) and BMI. Missing data were imputed using multiple imputation (MI) with data augmentation (Sinharay, Stern, & Russell, 2001). Data augmentation is a reliable and acceptable method for creating multiply imputed datasets (Sinharay et al., 2001). A linear regression model was used to determine the association of country of residence with BMI for participants exposed to an antipsychotic. Model 1 was unadjusted while model 2 further controlled for demographics (age, gender, education and social status). Model 3 further controlled for behaviors (number of cigarettes per day, use of alcohol [yes/no], having a drug problem [yes/no] and level of physical activity). Model 4 further controlled for biological variables (blood pressure and abdominal circumference). Model 5 further controlled for anxiety and depressive symptoms as well as psychiatric comorbidities such as the diagnosis of a mood disorder, psychosis or dementia. We considered differences significant at a two-tailed p<0.05. Analyses were performed using STATA version 13.1 (StataCorp, 2013).

Table 1.

Characteristics of Mexican and Colombian Participants Taking Antipsychotics (imputed data).

Mexico
(n=149)		 Colombia
(n=56)		 p-value
Age (SE) 37.1 (0.8) 48.7 (2.3) <0.001
Male (%) 93 (62) 25 (44) <0.001
Years Education (SE) 8.5 (0.3) 9.1 (0.5) 0.34
Subjective Social Status (SE) 3.5 (0.1) 4.4 (0.2) 0.01
Behaviors
Cigarette use/day (SE) 3.3 (6.5) 0.39 (1.6) <0.01
Has a drug problem (%) 14 (6) 3 (5) <0.001
Alcohol use (%) 18 (8) 3 (5) <0.001
Does Exercise (%)
        Never/Rare
        Sometimes
          Often
60 (91)
6 (9)
0
13 (23)
9 (16)
34 (61)		 <0.001
Biological
Systolic Blood Pressure (SE) 117.3 (1.2) 112.0 (2.0) 0.03
Dyastolic Blood Pressure (SE) 74.4 (1.1) 75.2 (1.4) 0.71
Abdominal Circumf (cm)(SE) 100.6 (1.5) 92.7 (1.6) 0.004
BMI (kg/m2)(SE) 29.8 (0.5) 25.5 (0.6) <0.001
Comorbidities
PHQ-9 (SE) 10.0 (0.5) 9.7 (0.8) 0.77
GAD-7 (SE) 7.7 (0.5) 8.2 (0.8) 0.57
Diagnosis of Psychosis (%) 45 (53) 19 (34) <0.001
Diagnosed Bipolar (%) 23 (27) 22 (39) 0.12
Diagnosed with Dementia (%) 0 7 (13) <0.001
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RESULTS

The sociodemographic characteristics of both samples are presented in Table 1. The mean age for Mexicans was 37.1 (SD=0.8) and 48.7 (SD=2.3) for Colombian patients. The mean BMI for Mexicans was 29.8 (SD=0.5) and 25.5 (SD=0.6) for Colombian patients (p<0.05).

In unadjusted, bivariate analyses (Model 1), a significant difference was found between BMI and country of residence (β=4.5; p<0.05). After controlling for demographic variables (Model 2), the difference between country of residence and BMI remained significant (β=4.7; p<0.05). Adding behaviors to demographic variables (Model 3) did not attenuate the association between country of residence and BMI (β=4.3; p<0.05). This difference remained significant (β=3.4; p<0.05) after adding biological variables (Model 4). Finally, after controlling for demographics, behaviors, biological and comorbid psychiatric variables (Model 5), there was a significant difference between Colombia vs. Mexico with the BMI of patients exposed to antipsychotics (β=4.9;p<0.05). Table 2 summarizes the results showing all the covariates. In Model 5, we also showed that BMI had also a significant association with years of education (β=0.12,p<0.05), alcohol problems (β=−4.25,p<0.05), systolic blood pressure (β=0.05,p<0,05), abdominal circumference (β=0.24,p<0.05), symptoms of depression (β=−0.15,p<0,05) and having a diagnosis of bipolar disorder (β=1.92,p<0.05).

Table 2.

Association of country of residence with BMI, adjusting for covariates.

BMI β SE 95% Conf. Interval p
Country   4.90 0.38   4.14, 5.66 <0.001
Age   0.00 0.00 −0.01, 0.02 0.53
Gender   0.20 0.27 −0.33, 0.75 0.45
Years of Education   0.12 0.29   0.06, 0.17 <0.001
Social Status −0.03 0.06 −0.16, 0.09 0.59
Cigarette use per day   0.04 0.02 −0.00, 0.10 0.08
Alcohol Problems −4.25 0.57 −5.39, −3.12 <0.001
Has a Drug Problem −1.14 0.59 −2.31, 0.01 0.05
Systolic Blood Pressure   0.05 0.00   0.04, 0.07 <0.001
Diastolic Blood Pressure   0.02 0.01 −0.00, 0.04 0.09
Abdominal Circumference   0.24 0.00   0.23, 0.25 <0.001
Anxiety Symptoms   0.03 0.02 −0.02, 0.09 0.27
Depressive Symptoms −0.15 0.02 −0.20, −0.09 <0.001
Diagnosis of Bipolar   1.92 0.34 1.24, 2.60 <0.001
Diagnosis of Psychosis −0.24 0.30 −0.84, 0.35 0.42
Diagnosis of Dementia −0.75 0.55 −1.85, 0.33 0.17
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*

Confidence Interval.

Country of Reference: Mexico

Model 1: Unadjusted

Model 2: Model 1+demographics (age, gender, education, social status).

Model 3: Model 2 + behaviors (#cigarettes/day, alcohol use and drug problem).

Model 4: Model 3 + biomarkers (blood pressure, abdominal circumference).

Model 5: Model 4 + anxiety and depressive symptoms, psychiatric comorbidities.

DISCUSSION

Our findings provide evidence of within-group differences among Latino patients (Colombia vs Mexico), and are consistent with the results of a previous study that identified differences between the Latinos from different heritage groups with cardiometabolic risk factors, such as obesity (Shargrodsky et al., 2008). These findings highlight the fact that Latinos should not be treated as a single or uniform group. Our hypotheses that there would be a significant association between country of residence and BMI and that Mexican patients would have higher BMI than their Colombian counterparts was supported. Much of the prior research investigating differences in cardiometabolic risk factors between diverse Latinos has focused on Latinos without mental illness and has not included participants who were at risk from their medications (e.g., antipsychotics) (Allison & Casey, 2001; Shargrodsky et al., 2008). These results suggest that differences in BMI in patients exposed to antipsychotics in Mexico and Colombia may reflect the differences in prevalence of overweight/obesity at the population level in the respective countries, and highlights the involvement of other risk factors, which may include genetics (Maina, Salvi, Vitalucci, D’Ambrosio, & Bogetto, 2008).

Obesity is more widespread in Mexico than Colombia, affecting all sectors of the population including those with a mental illness who are taking antipsychotics (Kasper, Herrán, & Villamor, 2014; OECD, 2016). In patients with severe mental illness (SMI), such as schizophrenia and major mood disorders, differences in BMI may be affected by the presence of the fat mass- and obesity-associated gene (FTO) risk alleles, especially in homozygous individuals for these variants. The FTO maps to chromosome 16 and it is considered the locus with the largest known effect on BMI and related phenotypes at different stages in life. Previous research has observed that FTO polymorphisms confer a highly significant association with obesity, suggesting that FTO is a major susceptibility gene for obesity in the Mexican population (Díaz-Anzaldúa et al., 2015; Villalobos-Comparán et al., 2008). The FTO gene has been considered a genetic risk factor for BMI increments in several populations, including samples of Mexican Mestizos in Mexico and in the US with SMI (Díaz-Anzaldúa et al., 2015; Frayling et al. 2007; Villalobos-Comparán et al., 2008). In our sample, there may have been a larger number of carriers of the risk allele in the Mexican sample compared to Colombian sample with each extra copy of the risk allele being more strongly associated with BMI.

Caution is warranted in interpreting our results due to limitations associated with the sample, study methods, and design. First, the cross-sectional nature of the study with a small number of Colombians relative to the number of Mexicans may have limited our power. Second, the Colombian participants were recruited from only one clinic in Bogotá. These individuals represent a select subgroup, and conclusions drawn may not be generalizable to the population at large. Third, the non-longitudinal design precludes from inferences about causality. Fourth, it was not possible to collect serum biomarkers of metabolism in all the subjects. This prevented us from detecting differences in other cardiometabolic risk factors. The inability to collect this data was a result of lack of funds or medical insurance to cover for such an expense and lack of compliance from the patients. Fifth, we used country of residence as a proxy for ethnicity. Prior research has demonstrated that country of residence may affect the way an individual self-selects their race and ethnicity (Lopez, Bevans, Wehrlen, Yang, & Wallen, 2017). For example, in our study, there may have been individuals who identified more with their Amerindian heritage rather than their Spanish ancestry and may not have identified as Latino.

In conclusion, there are substantial sociocultural differences between Latino groups, including differences in health risks that are likely the result of the known cultural, genetic and socioeconomic heterogeneity of this population. Despite the known contribution of ethnicity and chronic mental illness to cardiometabolic risk, few studies have identified the effect of atypical antipsychotic exposure with modifiable cardiometabolic risk factors in specific ethnic groups. Results of this multisite, international, cross sectional study of adult Latino patients exposed to antipsychotics in two Latin-American Countries (i.e. Mexico and Colombia) showed a significant difference with the BMI of patients exposed to antipsychotics. Besides evaluating the possible metabolic effects of certain antipsychotics, it is important to evaluate the role of other factors such as FTO risk alleles.

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