Age-specific Sex Differences Research Articles

Risky business: sex differences in mortality and dispersal in a polygynous, monomorphic lemur

Sexually selected traits and the use of strategies to enhance male reproductive success (e.g., competition and dispersal) can yield sex differences in metabolic requirements, rates and durations of growth and maturation, and the propensity for risky behavior, which are suggested to result in age-specific sex differences in mortality and life span. We investigated age-specific sex ratios, mortality, and dispersal in Propithecus edwardsi in Ranomafana National Park, Madagascar. We predicted that, due to similarities in growth rates and body sizes, male and female juvenile mortality rates would be comparable; because both sexes disperse and have intense intersexual competition and aggression, adult mortality would be similar; given similarities in dispersal frequency and distance, the timing of dispersal would not differ. We used 80 group-years births, deaths, and dispersals (N females = 41, N males = 34) collected over 23 years to calculate sex ratios and survival curves. Females lived longer than males (maximum 32 and 19 years, respectively). Sex ratios were male biased from sexual maturity through 17 years and female biased at birth and older ages. Infant survival probabilities were similar. Thus, differential development and maturation are unlikely explanations for longer female life span in this species. Males were more likely to survive from 2 to 18 years. However, male annual survival probability declined quickly around 13–18 years; males continued to disperse until their deaths, whereas females generally stopped dispersing after 11 years. We suggest that sex differences in the timing of dispersal and the unique challenges of risky behavior at older ages may be sufficient to yield differences in male and female life span.

Age- and sex-specific rates of leukoaraiosis in TIA and stroke patients

To determine any sex differences in age-specific prevalence or severity of leukoaraiosis, a marker of white matter ischemia, in population-based and clinic cohorts of TIA/stroke and in a systematic review of the literature. Age-specific sex differences were calculated for both CT and MRI in the Oxford Vascular Study (OXVASC) and in an MRI-based clinic cohort. We pooled odds ratios (ORs) for leukoaraiosis in women vs men from published studies by fixed-effect meta-analysis, stratified by patient characteristics (stroke vs nonstroke) and CT vs MRI. Among 10 stroke studies (all CT-based), leukoaraiosis was most frequent in women (OR = 1.42, 95% confidence interval [CI] 1.27-1.57, p < 0.0001), with little heterogeneity between studies (p = 0.28). However, no such excess was seen in 10 reports of nonstroke cohorts (0.91, 0.67-1.24, p = 0.56). Moreover, excess leukoaraiosis in women on CT-imaging in OXVASC (1.38, 1.15-1.67, p = 0.001) was explained by their older age (age-adjusted OR = 1.01, 0.82-1.25, p = 0.90). Leukoaraiosis was more severe in older (≥ 75) women (CT-1.50, 1.14-1.97, p = 0.004 in OXVASC; MRI-1.70, 1.17-2.48, p = 0.006 in OXVASC and clinic cohort). However, leukoaraiosis was independently associated with early mortality (hazard ratio = 1.46, 1.23-1.73, p < 0.0001), suggesting that comparisons in older age groups will be biased by prior premature death of men with leukoaraiosis. Sex differences in severity of leukoaraiosis were not addressed in previous studies. Previously reported excess leukoaraiosis in women with TIA/stroke is likely to be confounded by age and apparently greater severity in older women is likely to be biased by premature death in men with leukoaraiosis.

ACUTE MYOCARDIAL INFARCTION

Women with acute myocardial infarction have higher in-hospital mortalitythan men mainly due to greater age on presentation. Objective: To evaluate the age specific sex difference in inhospitalmortality of acute myocardial infarction. Design: Descriptive study. Place and duration: Coronary Care Unitand cardiology ward of Nishtar Hospital Multan from 15 of th September 2002 till 30th of April 2003. Material &amp; Methods:Four hundred and fifty patients of acute myocardial infarction who fulfilled our inclusion criteria were studied while theywere admitted to the hospital. Patients were divided into four groups according to age and sex i.e. Group I (male &lt;45years), Group II (male $45 years), Group III (female &lt;45 years) and Group IV (female $45 years). In-hospital mortalitywas compared between different age groups by Chi-square test. Results: The total in-hospital mortality was76(16.9%).In Group III none of the patients expired. In Group I in-hospital mortality was 6(7.1%) patients followed byGroup II 50(18.3%) patients and Group IV 20(23.3%) patients p&lt;0.019. In-hospital mortality was greater in Group IVthan in any other group. Group IV patients were more frequently diabetic and hypertensive than patients in any othergroup. Group IV patients presented late to the hospital. There was no significant difference in site of myocardialinfarction in different groups. Higher Killip class was observed in Group II and IV p&lt;0.05. Streptokinase injection wasgiven less frequently in Group IV than in any other group p &lt;0.012. Only 34(39.5%) patients in Group IV had nocomplication during hospital stay while more patients in other groups had uneventful hospital stay p&lt;0.001.Conclusion: Female sex is associated with higher in-hospital mortality in older age group as compared to the malepatients of same age group.

ACUTE MYOCARDIAL INFARCTION

Women with acute myocardial infarction have higher in-hospital mortalitythan men mainly due to greater age on presentation. Objective: To evaluate the age specific sex difference in inhospitalmortality of acute myocardial infarction. Design: Descriptive study. Place and duration: Coronary Care Unitand cardiology ward of Nishtar Hospital Multan from 15 of th September 2002 till 30th of April 2003. Material &amp; Methods:Four hundred and fifty patients of acute myocardial infarction who fulfilled our inclusion criteria were studied while theywere admitted to the hospital. Patients were divided into four groups according to age and sex i.e. Group I (male &lt;45years), Group II (male $45 years), Group III (female &lt;45 years) and Group IV (female $45 years). In-hospital mortalitywas compared between different age groups by Chi-square test. Results: The total in-hospital mortality was76(16.9%).In Group III none of the patients expired. In Group I in-hospital mortality was 6(7.1%) patients followed byGroup II 50(18.3%) patients and Group IV 20(23.3%) patients p&lt;0.019. In-hospital mortality was greater in Group IVthan in any other group. Group IV patients were more frequently diabetic and hypertensive than patients in any othergroup. Group IV patients presented late to the hospital. There was no significant difference in site of myocardialinfarction in different groups. Higher Killip class was observed in Group II and IV p&lt;0.05. Streptokinase injection wasgiven less frequently in Group IV than in any other group p &lt;0.012. Only 34(39.5%) patients in Group IV had nocomplication during hospital stay while more patients in other groups had uneventful hospital stay p&lt;0.001.Conclusion: Female sex is associated with higher in-hospital mortality in older age group as compared to the malepatients of same age group.

Growth status and obesity of Hopi children.

The purpose of this study was to examine the growth status and prevalence of underweight, overweight, and obesity in Hopi children. Subjects were 263 (117 males, 146 females) Hopi children 6-12 years of age. Stature and mass were measured and the body mass index (BMI) was calculated. Body size variables were plotted relative to age- and sex-specific reference data and the prevalence rates for underweight, overweight, and obesity were estimated using the BMI as the criterion. Age-specific sex differences were compared using independent samples t-tests. In both sexes, mean age-specific stature appeared to be relatively stable around the 50th percentile of reference values. Mean age-specific mass appeared to be relatively stable between the 50th and 90th percentiles of the reference values, while the mean BMI tended to fluctuate about the 85th percentile. Approximately 23% of Hopi children were classified as overweight and an additional 24% were classified as obese. Only two subjects were categorized as underweight. The results are consistent with other reports that childhood obesity is a serious public health concern among Native Americans. Further study is warranted to examine the causes of the high prevalence rates of pediatric obesity among Native Americans and the effectiveness of prevention and intervention programs.

Sex differences in survival after myocardial infarction in Sweden; data from the Swedish National Acute Myocardial Infarction Register.

Women, particularly younger women, hospitalized with acute myocardial infarction have been found to have poorer prognosis than men. A large proportion of deaths due to myocardial infarction, however, occur in the pre-hospital phase. We set out to analyse age-specific sex differences in survival after myocardial infarction at different time intervals from the onset of acute myocardial infarction, including pre-hospital deaths and 1-year overall survival. The National Acute Myocardial Infarction Register in Sweden was used to analyse age-specific sex differences in mortality outside hospital, 28-day mortality and 1-year mortality in 353 905 cases occurring between 1987 and 1995 in Swedish men and women aged 30 to 89 years. Overall, one in four of all myocardial infarction victims died outside hospital. At all ages, except in individuals younger than 50 years, men had higher pre-hospital mortality. The odds of dying within 28 days for women below 50 years of age, compared to men, was 1.84 (1.56--2.18) in hospitalized patients and 1.31 (1.18--1.46) in all infarction patients. Above the age of 65, in the total population with myocardial infarction, women had a better prognosis, with odds ratios ranging from 0.83 to 0.89. In patients surviving the first 28 days, 4.0% of the women and 2.9% of the men below the age of 50 were dead within a year after the infarction, odds ratio 1.37 (1.06--1.76). This excess mortality was mainly due to diabetes and non-cardiac causes. Only women younger than 50 years had a significantly poorer overall 1-year survival than men of the same age. At the age of 70 or more, women had a small survival advantage. In the total acute myocardial infarction population, only women under 50 years of age have a consistently worse prognosis than men. Much of the excess mortality in young women seems to be associated with diabetes.

Growth and overweight of Navajo youth: secular changes from 1955 to 1997.

To examine the growth status, prevalence of risk of overweight and of overweight, and secular changes in growth status in Navajo youth from 1955 to 1997. 526 (256 males, 270 females) Navajo children 6-12 y of age. Stature and mass were measured and the body mass index (BMI) was calculated. All three variables were plotted relative to age- and sex-specific US reference data and the prevalence rates for risk of overweight and of overweight were estimated using the BMI as the criterion. The cut-off for the risk of overweight was the age- and sex-specific 85th and 95th percentiles of NHANES I, while the cut-off for overweight was a BMI>/=95th percentiles. Age-specific sex differences were compared using independent samples t-tests. Secular changes for body size were estimated by comparing age- and sex-specific means for stature, mass, and the BMI in the present study and two previous studies in 1955 and 1989. No statistically significant differences were observed between sexes within age groups. In both sexes, mean age-specific stature appeared to be relatively stable around the 50th percentile of US reference values. Mean age-specific mass appeared to be relatively stable between the 50th and 90th percentiles of the reference values, while the mean BMI tended to fluctuate about the 85th percentile. Approximately 41% of the Navajo boys and girls 6-12 y of age had BMIs >/=85th percentiles of US reference data. Compared to corresponding data on Navajo youth in 1955 and 1989, the current sample was larger in mass and the BMI. The estimated rate of secular change in mass was about 1.5 kg/decade in younger boys and girls, and about 3 kg/decade in older boys and girls between 1955 and 1997. The estimated rate of secular change in the BMI was about 0.5-1.0 units/decade between 1955 and 1997, while that for stature was about 2 cm/decade between 1955 and 1997. The results are consistent with recent findings on the Navajo Health and Nutrition Survey that overweight is a serious public health concern across the lifespan in the Navajo, and that the problem begins in childhood. Furthermore, Navajo children appear to be heavier than about a decade ago. International Journal of Obesity (2000) 24, 211-218