Childbearing May Increase the Risk of Nondiabetic Cataract in Chinese Women's Old Age

Timing of first childbirth and age-related cataract

OBJECTIVE

No studies investigated the effects of age at first childbirth on cataract formation. This study was performed to determine the relationships of age at first childbirth to age-related cataract in postmenopausal women.

METHODS

Study population included 7,021 postmenopausal women in the Korea National Health and Nutrition Examination Survey, 2008 to 2012. Participants were subdivided in quartiles according to the age at first childbirth as follows: 13 to 21, 22 to 23, 24 to 25, and 26 to 44 years. We used odds ratios (ORs) and 95% confidence intervals (CIs) to address the relationships between age at first childbirth and age-related cataract with adjustments for confounders.

RESULTS

Mean participants' age and age at first childbirth were 64.4 and 23.6 years, respectively. The prevalence of any subtype of age-related cataract was 64.9%. Nuclear cataract prevalence was significantly higher in postmenopausal women with later age at first childbirth (24-25 and 26-44 years) compared with those with the earliest age at first childbirth (13-21 years): ORs (95% CIs) were 1.23 (1.05-1.45) and 1.24 (1.05-1.46), respectively. A significant linear trend across quintile was observed (P = 0.006). Age at first childbirth linearly 4% (OR 1.04, 95% CI 1.01-1.06) and 2% (OR 1.02, 95% CI 1.00-1.04) increased risk for nuclear and cortical cataract formation, respectively. The population-attributable fraction of nuclear cataract caused by the first childbirth at 24 years or later was 4.9% (95% CI 1.20%-8.59%, P = 0.009).

CONCLUSIONS

Later age of first childbirth was independently associated with higher risks of nuclear and cortical cataract in postmenopausal women. Further prospective studies are needed to elucidate the role of age at first childbirth in developing age-related cataract.

Effect of Resting Heart Rate on All-Cause Mortality and Cardiovascular Events According to Age

OBJECTIVES

To examine whether the association between resting heart rate (RHR) and all-cause mortality and cardiovascular events differs according to age.

DESIGN

Prospective cohort.

SETTING

Community in Beijing, China.

PARTICIPANTS

Individuals aged 40 and older without cardiovascular disease at baseline (N = 6,209).

MEASUREMENTS

Trained investigators interviewed participants using a standard questionnaire to obtain information on demographic characteristics, medical history and lifestyle risk factors in 1991. RHR was evaluated according to quartiles (<72, 72-76, 76-84, ≥84 beats/min). Cox regression models were used to assess the associations between RHR and all-cause mortality and cardiovascular events.

RESULTS

During a mean follow-up of 8.3 years, 840 subjects died, and 676 experienced a cardiovascular event. Higher RHR was significantly associated with all-cause mortality (P trend < .001) and cardiovascular events (P trend = .002) in older (≥60) but not younger (<60) participants (both P trend > .05). There were significant modifying effects of age on the association between RHR and all-cause mortality (P interaction < .001) and cardiovascular events (P interaction =.002). Similar results were observed after exclusion of individuals who died (n = 100) or had a cardiovascular event (n = 45) during the first 2 years of follow-up.

CONCLUSION

High RHR appears to be an independent determinant of all-cause mortality and cardiovascular events in older but not younger individuals.