529331 research-article2014
JAHXXX10.1177/0898264314529331Journal of Aging and HealthDe la Cruz-Góngora et al.
Article
Short-Term Impact of Anemia on Mortality: Evidence From a Sample of Mexican Older Adults
Journal of Aging and Health 2014, Vol. 26(5) 750–765 © The Author(s) 2014 Reprints and permissions: sagepub.com/journalsPermissions.nav DOI: 10.1177/0898264314529331 jah.sagepub.com
Vanessa De la Cruz-Góngora, MSc1, Betty Manrique-Espinoza, PhD1, Salvador Villalpando, MD, PhD1, Martha María Téllez-Rojo Solís, PhD1, and Aarón Salinas-Rodriguez, MSc1
Abstract Objective: To estimate the short-term (14 months) impact of anemia on mortality among Mexican older adults (OAs). Method: Longitudinal analyses using data from a quasi-experimental study in a non-contributory pension program in Mexico with a sample of 3,621 OAs aged 65 to 74 years. Data on health, nutrition, life conditions, and mortality were gathered at both baseline and follow-up. Logistic regression model was used to estimate the impact of anemia and hemoglobin quintiles on mortality. Results: Overall mortality rate was 2.1%. Both mild anemia and moderate/ severe anemia increased mortality risk at 14 months (odds ratio [OR] = 2.04, 95% confidence interval [CI] = [1.1, 4.1]; and OR = 6, 95% CI = [2.1, 16.9], respectively). Discussion: In the short term, degree of severity of anemia is an independent predictor of mortality risk. Because anemia is a modifiable factor, further research is required to better understand this condition in terms of main causes, prevention, treatment, and impact on OAs’ survival.
1National
Institute of Public Health, Cuernavaca, Mexico
Corresponding Author: Aarón Salinas-Rodriguez, MSc, Instituto Nacional de Salud Pública, Av. Universidad 655, Col. Santa María Ahuacatitlán. Cuernavaca, Morelos, México. Email: [email protected]
Downloaded from jah.sagepub.com at Univ of Connecticut / Health Center / Library on May 12, 2015
De la Cruz-Góngora et al.
751
Keywords anemia, mortality, Mexican older adults
Introduction Anemia is a highly prevalent condition among older adults (OAs), especially among males. Data from National Health and Nutrition Survey in Mexico showed that the prevalence of anemia in OAs was 18.35% in males, 17.35% in females, and reached 31% in OAs aged 80 years and above. Prevalence in rural areas was 20.64% in males and 15.6% in females (Gutiérrez et al., 2012). There is growing evidence that lower hemoglobin (Hb) concentrations constitute a pathological condition in the elderly, and not a normal consequence of aging (Nissenson, Goodnough, & Dubois, 2003). Anemia in OAs has been linked to high morbidity (Patel, 2008), poor functional status (den Elzen et al., 2009), cognitive decline and dementia (Peters et al., 2008), increased risk of hospitalization, and mortality (Riva et al., 2009). In the same vein, higher Hb concentrations have been associated with higher risk of mortality. In a sample of American OAs, risk of mortality was tied to the lowest and highest quintiles of Hb concentration (Zakai et al., 2005). Similarly, mild anemia has been identified as an independent predictor of mortality among OAs in developed countries (Peters et al., 2008). While former studies have estimated the prognosis of anemia in severely ill patients over a short period of time (Price, Mehra, Holmes, & Schrier, 2011), whether differences exist with regard to the severity of anemia prognosis of ambulatory OAs over a short period of time has not been widely documented. The objective of this study was to estimate the short-term (14 months) impact of anemia on mortality among ambulatory OAs residing in rural localities in Mexico. In this study, we used the term ambulatory older adults to highlight that OAs were able to carry out some basics activities of daily living (walking, eating, bathing, etc.) and not to be severely ill to be hospitalized or be in bed at time of interview.
Method Study Design and Sampling OAs in our sample were part of the impact evaluation study of Program “70 y más” conducted in Mexico during the years 2007-2009. Implemented nationally throughout Mexico, Program 70 y más was aimed at improving the living conditions among adults aged 70 years and older by boosting their
Downloaded from jah.sagepub.com at Univ of Connecticut / Health Center / Library on May 12, 2015
752
Journal of Aging and Health 26(5)
social protection through policy mechanisms. Centered on two components, 70 y más pursues a twofold objective: (a) to raise the income of the elderly and (b) to improve the social protection of the elderly. Under the first program objective, elderly receive a direct unconditional cash transfer of 500 Mexican pesos (approximately US$40) every month, which can be collected every 2 months. Following is a brief description of the program impact evaluation design. In 2007, the Ministry of Social Development established two criteria for selecting program beneficiaries: first, being ≥70 years old and, second, residing in a rural locality of ≤2,500 inhabitants.1 Both were used in the impact evaluation study as the basis for setting up four study groups. Power analysis and sample size calculation determined a total of 6,000 OAs distributed in four study groups (1,500 per group). According to an empirical comparison group formation analysis, it was determined that OAs aged between 65 and 74 years would be included in the evaluation study, with an intervention group composed of OAs aged 70 to 74 years residing in rural areas. The remaining OAs were distributed among three control groups. The first included OAs, aged 70 to 74 years, living in communities slightly larger than rural localities (2,501-2,700 inhabitants); the second, OAs aged 65 to 69 years, living in rural localities; and the third, OAs aged 65 to 69 years, living in localities of 2,501-2,700 inhabitants. Impact evaluation study was conducted in 516 Mexican rural localities. The 70 y más Program description, methodological details of evaluation design, and the sampling procedures and results have been previously reported (Salinas-Rodríguez et al., 2013). We used the same analytical sample for analyses in this work, but restricting to OAs who had all biological measurements (see next paragraph), and we used the information from the four evaluation groups only as a control variable in the statistical analysis.
Data Collection Data on health, nutrition, and life conditions were gathered both at baseline (in 2007) and at intervals of 11 (in 2008) and 14 (in 2009) months. Information on OA death was collected in 2008 and 2009 for all participants in the study. This information was obtained from the household key informant if OA not lived alone and the proxy informant if OA lived alone. The follow-up periods were planned according to the evaluation design in the original study. Information included demographic and socioeconomic data collected during interviews by trained personnel from the National Institute of Public Health of Mexico. Eligible participants numbered 6,000 OAs at baseline, and capillary blood specimens were collected by finger puncture from a sample of
Downloaded from jah.sagepub.com at Univ of Connecticut / Health Center / Library on May 12, 2015
De la Cruz-Góngora et al.
753
4,288 OAs to measure their Hb levels in portable Hemocue photometers. However, complete information on all variables and blood samples were obtained from 3,621 OAs (Figure 1).
Definition of Variables Outcome. The OA death was registered only in those cases where the household key informant or proxy informant declared that elderly has died from any cause. The causes of death were registered and classified on the basis of death certificates from the clinics nearest the OA households. Exposure variable. We explored three different ways of analyzing the impact of anemia on mortality. First, anemia was defined as a dummy variable equal to 1 where Hb concentration, adjusted by altitude as recommended by the World Health Organization (WHO; Cohen & Hass, 1999), was
JAHXXX10.1177/0898264314529331Journal of Aging and HealthDe la Cruz-Góngora et al.
Article
Short-Term Impact of Anemia on Mortality: Evidence From a Sample of Mexican Older Adults
Journal of Aging and Health 2014, Vol. 26(5) 750–765 © The Author(s) 2014 Reprints and permissions: sagepub.com/journalsPermissions.nav DOI: 10.1177/0898264314529331 jah.sagepub.com
Vanessa De la Cruz-Góngora, MSc1, Betty Manrique-Espinoza, PhD1, Salvador Villalpando, MD, PhD1, Martha María Téllez-Rojo Solís, PhD1, and Aarón Salinas-Rodriguez, MSc1
Abstract Objective: To estimate the short-term (14 months) impact of anemia on mortality among Mexican older adults (OAs). Method: Longitudinal analyses using data from a quasi-experimental study in a non-contributory pension program in Mexico with a sample of 3,621 OAs aged 65 to 74 years. Data on health, nutrition, life conditions, and mortality were gathered at both baseline and follow-up. Logistic regression model was used to estimate the impact of anemia and hemoglobin quintiles on mortality. Results: Overall mortality rate was 2.1%. Both mild anemia and moderate/ severe anemia increased mortality risk at 14 months (odds ratio [OR] = 2.04, 95% confidence interval [CI] = [1.1, 4.1]; and OR = 6, 95% CI = [2.1, 16.9], respectively). Discussion: In the short term, degree of severity of anemia is an independent predictor of mortality risk. Because anemia is a modifiable factor, further research is required to better understand this condition in terms of main causes, prevention, treatment, and impact on OAs’ survival.
1National
Institute of Public Health, Cuernavaca, Mexico
Corresponding Author: Aarón Salinas-Rodriguez, MSc, Instituto Nacional de Salud Pública, Av. Universidad 655, Col. Santa María Ahuacatitlán. Cuernavaca, Morelos, México. Email: [email protected]
Downloaded from jah.sagepub.com at Univ of Connecticut / Health Center / Library on May 12, 2015
De la Cruz-Góngora et al.
751
Keywords anemia, mortality, Mexican older adults
Introduction Anemia is a highly prevalent condition among older adults (OAs), especially among males. Data from National Health and Nutrition Survey in Mexico showed that the prevalence of anemia in OAs was 18.35% in males, 17.35% in females, and reached 31% in OAs aged 80 years and above. Prevalence in rural areas was 20.64% in males and 15.6% in females (Gutiérrez et al., 2012). There is growing evidence that lower hemoglobin (Hb) concentrations constitute a pathological condition in the elderly, and not a normal consequence of aging (Nissenson, Goodnough, & Dubois, 2003). Anemia in OAs has been linked to high morbidity (Patel, 2008), poor functional status (den Elzen et al., 2009), cognitive decline and dementia (Peters et al., 2008), increased risk of hospitalization, and mortality (Riva et al., 2009). In the same vein, higher Hb concentrations have been associated with higher risk of mortality. In a sample of American OAs, risk of mortality was tied to the lowest and highest quintiles of Hb concentration (Zakai et al., 2005). Similarly, mild anemia has been identified as an independent predictor of mortality among OAs in developed countries (Peters et al., 2008). While former studies have estimated the prognosis of anemia in severely ill patients over a short period of time (Price, Mehra, Holmes, & Schrier, 2011), whether differences exist with regard to the severity of anemia prognosis of ambulatory OAs over a short period of time has not been widely documented. The objective of this study was to estimate the short-term (14 months) impact of anemia on mortality among ambulatory OAs residing in rural localities in Mexico. In this study, we used the term ambulatory older adults to highlight that OAs were able to carry out some basics activities of daily living (walking, eating, bathing, etc.) and not to be severely ill to be hospitalized or be in bed at time of interview.
Method Study Design and Sampling OAs in our sample were part of the impact evaluation study of Program “70 y más” conducted in Mexico during the years 2007-2009. Implemented nationally throughout Mexico, Program 70 y más was aimed at improving the living conditions among adults aged 70 years and older by boosting their
Downloaded from jah.sagepub.com at Univ of Connecticut / Health Center / Library on May 12, 2015
752
Journal of Aging and Health 26(5)
social protection through policy mechanisms. Centered on two components, 70 y más pursues a twofold objective: (a) to raise the income of the elderly and (b) to improve the social protection of the elderly. Under the first program objective, elderly receive a direct unconditional cash transfer of 500 Mexican pesos (approximately US$40) every month, which can be collected every 2 months. Following is a brief description of the program impact evaluation design. In 2007, the Ministry of Social Development established two criteria for selecting program beneficiaries: first, being ≥70 years old and, second, residing in a rural locality of ≤2,500 inhabitants.1 Both were used in the impact evaluation study as the basis for setting up four study groups. Power analysis and sample size calculation determined a total of 6,000 OAs distributed in four study groups (1,500 per group). According to an empirical comparison group formation analysis, it was determined that OAs aged between 65 and 74 years would be included in the evaluation study, with an intervention group composed of OAs aged 70 to 74 years residing in rural areas. The remaining OAs were distributed among three control groups. The first included OAs, aged 70 to 74 years, living in communities slightly larger than rural localities (2,501-2,700 inhabitants); the second, OAs aged 65 to 69 years, living in rural localities; and the third, OAs aged 65 to 69 years, living in localities of 2,501-2,700 inhabitants. Impact evaluation study was conducted in 516 Mexican rural localities. The 70 y más Program description, methodological details of evaluation design, and the sampling procedures and results have been previously reported (Salinas-Rodríguez et al., 2013). We used the same analytical sample for analyses in this work, but restricting to OAs who had all biological measurements (see next paragraph), and we used the information from the four evaluation groups only as a control variable in the statistical analysis.
Data Collection Data on health, nutrition, and life conditions were gathered both at baseline (in 2007) and at intervals of 11 (in 2008) and 14 (in 2009) months. Information on OA death was collected in 2008 and 2009 for all participants in the study. This information was obtained from the household key informant if OA not lived alone and the proxy informant if OA lived alone. The follow-up periods were planned according to the evaluation design in the original study. Information included demographic and socioeconomic data collected during interviews by trained personnel from the National Institute of Public Health of Mexico. Eligible participants numbered 6,000 OAs at baseline, and capillary blood specimens were collected by finger puncture from a sample of
Downloaded from jah.sagepub.com at Univ of Connecticut / Health Center / Library on May 12, 2015
De la Cruz-Góngora et al.
753
4,288 OAs to measure their Hb levels in portable Hemocue photometers. However, complete information on all variables and blood samples were obtained from 3,621 OAs (Figure 1).
Definition of Variables Outcome. The OA death was registered only in those cases where the household key informant or proxy informant declared that elderly has died from any cause. The causes of death were registered and classified on the basis of death certificates from the clinics nearest the OA households. Exposure variable. We explored three different ways of analyzing the impact of anemia on mortality. First, anemia was defined as a dummy variable equal to 1 where Hb concentration, adjusted by altitude as recommended by the World Health Organization (WHO; Cohen & Hass, 1999), was
