To investigate the association of resting heart rate with suicide in two large cohorts.
The MJ cohort (Taiwan) included 532 932 adults from a health check-up programme (1994-2008). The HUNT cohort (Norway) included 74 977 adults in the Nord-Trøndelag County study (1984-1986), followed up to 2004. In both cohorts heart rate was measured at baseline, and suicide was ascertained through linkage to cause-of-death registers. Risk of suicide was estimated using Cox proportional hazards models.
There were 569 and 188 suicides (average follow-up period of 8.1 and 16.9 years) in the MJ and HUNT cohorts respectively. Sex- and age-adjusted hazard ratio for every 10 beat increase in heart rate per minute was 1.08 (95% Confidence Interval 1.00-1.16) and 1.24 (1.12-1.38) in the MJ and HUNT cohorts, respectively. In the MJ cohort this association was confined to individuals with a history of heart diseases vs. those without such a history (P for interaction = 0.008). In the HUNT cohort the association did not differ by history of heart diseases and was robust to adjustment for health-related life style, medication use, and symptoms of anxiety and depression.
Elevated resting heart rate may be a marker of increased suicide risk.
AIM: To assess the change of risk factors that are specific to sudden infant death syndrome (SIDS) after the initialization of a campaign to reduce the risk (RTR) of SIDS compared to non-SIDS postneonatal deaths. METHODS: Data were extracted from the Swedish Medical Birth Registry, 1982-1991 and 1993-1998. 1105 infants died from SIDS during the postneonatal period. 2115 postneonatal deaths were from other causes and 11,050 live birth controls were selected. Risk factors previously identified to be related to SIDS were defined as high parity, prematurity, young maternal age, low Apgar score, birth during the night, single motherhood, multiple births, maternal smoking, male gender, short length standard deviation score (SDS) and small weight-to-length SDS. RESULTS: Non-SIDS deaths were more significantly related to a low 5-min Apgar score, smaller weight-to-length SDS, and/or short length SDS values; while SIDS deaths were more closely related to mothers with higher parity or multiple births, mothers who smoked during pregnancy and single-parent (mother) families. Maternal smoking was even more prominent among SIDS deaths in the post-campaign period. The adjusted odds ratios, compared with non-SIDS deaths, increased from 1.84 (95% CI: 1.48, 2.28) in the pre-campaign period to 4.11 (95% CI: 2.72, 6.21) in the post-campaign period. CONCLUSIONS: Maternal smoking during pregnancy remains the most important modifiable risk factor for SIDS in the post-campaign period in comparison with non-SIDS postneonatal deaths. Other than putting babies in a supine sleeping position, maternal smoking should be the next most important issue to be considered, if there is to be a second campaign.
Birthweight is a crude indicator of size at birth. Some neonatologists and obstetricians have advocated the use of ponderal index and birthlength to characterize size at birth. This paper examines the associations between various size-at-birth indicators and neonatal and postneonatal mortality, with an emphasis on ponderal index and birthlength. Size at birth, gestational age and mortality data for about one million babies born alive in Sweden between 1987 and 1995 were collected from the Swedish Medical Birth Registry. A multinomial logit regression was used to estimate conditional odds ratios. Birthlength and ponderal index were independently associated with neonatal and postneonatal mortality. In the latter period, ponderal index was only weakly associated with mortality. The associations were not sensitive to exclusion of cases of congenital anomalies and adjustment for gestational age. Conclusion: Birthlength is strongly associated with both neonatal and postneonatal mortality; ponderal index is strongly associated with neonatal, but weakly with postneonatal mortality. The findings are consistent with previous hypotheses about a transient effect of ponderal index and a persistent effect of birthlength.