The increased survival of preterm and very low birth weight infants in recent years has been well documented but continued surveillance is required in order to monitor the effects of new therapeutic interventions. Gestation and birth weight specific survival rates most accurately reflect the outcome of perinatal care. Our aims were to determine survival to discharge for a large Canadian cohort of preterm infants admitted to the neonatal intensive care unit (NICU), and to examine the effect of gender on survival and the effect of increasing postnatal age on predicted survival.
Outcomes for all 19,507 infants admitted to 17 NICUs throughout Canada between January 1996 and October 1997 were collected prospectively. Babies with congenital anomalies were excluded from the study population. Gestation and birth weight specific survival for all infants with birth weight
Acute decompensated heart failure is the most common cause of hospitalization for patients older than 65 years of age. Although treatment of this condition has improved over the past two decades, the specific approach to patients in the acute setting has not evolved in the same way. A patient facing acute decompensation is experiencing a serious medical condition that is associated with a poor prognosis. In addition, acute decompensated heart failure results in significant costs to the health care system. Significant morbidity and mortality are associated with patients who are readmitted within a year of the first hospitalization. Because of this important problem, further research on improving the prognosis for this condition is warranted. The present article will focus on the risk factors associated with acute decompensation and the importance of this condition, both on prognosis and economics.
The ongoing Childhood Leukemia Survival Study is examining the possible association between magnetic field exposure and survival of children with newly diagnosed acute lymphocytic leukemia (ALL). We report the results of the first year 24 h personal magnetic field monitoring for 356 US and Canadian children by time weighted average TWA and alternative exposure metrics. The mean TWA of 0.12 microT was similar to earlier personal exposure studies involving children. A high correlation was found between 24 h TWA and alternative metrics: 12 h day TWA, 12 night TWA, geometric mean, 95th percentile value, percentage time over 0.2 and 0.3 microT, and an estimate of field stability (Constant Field Metric). Two measures of field intermittency, rate of change metric (RCM) and standardized rate of change metric (RCMS), were not highly correlated with TWA. The strongest predictor of TWA was location of residence, with highest TWAs associated with urban areas. Residence in an apartment, lower paternal educational level, and residential mobility were also associated with higher TWAs. There were no significant differences in the appliance use patterns of children with higher TWA values. Children with the highest field intermittency (high RCM) were more likely to sit within 3 feet of a video game attached to the TV. Our results suggest that 24 h TWA is a representative metric for certain patterns of exposure, but is not highly correlated with two metrics that estimate field intermittency.
Studies of radiation-associated risks among workers chronically exposed to low doses of radiation are important, both to estimate risks directly and to assess the adequacy of extrapolations of risk estimates from high-dose studies. This paper presents results based on a cohort of 45,468 nuclear power industry workers from the Canadian National Dose Registry monitored for more than 1 year for chronic low-dose whole-body ionizing radiation exposures sometime between 1957 and 1994 (mean duration of monitoring = 7.4 years, mean cumulative equivalent dose = 13.5 mSv). The excess relative risks for leukemia [excluding chronic lymphocytic leukemia (CLL)] and for all solid cancers were 52.5 [95% confidence interval (CI): 0.205, 291] and 2.80 (95% CI: -0.038, 7.13) per sievert, respectively, both associations having P values close to 0.05. Relative risks by dose categories increased monotonically for leukemia excluding CLL but were less consistent for all solid cancers combined. Although the point estimates are higher than those found in other studies of whole-body irradiation, the difference could well be due to chance. Further follow-up of this cohort or the combination of results from multiple worker studies will produce more stable estimates and thus complement the risk estimates from higher-dose studies.
To provide an empirical evaluation of the performance of period analysis in comparison to traditional methods of survival analysis for predicting future 5-year cancer survival using data from the Canadian Cancer Registry.
5-year relative survival estimates were derived by period and traditional methods of analysis using data available at the conclusion of 1997. The extent to which these estimates agreed with survival later observed for cancer cases diagnosed in 1997 was quantified by calculating the squared difference of the estimate to the corresponding relative survival ratio actually observed.
Period analysis was observed to be superior to, or comparable with, cohort analysis in predicting the average 5-year relative survival observed later for virtually all individual cancer sites studied. The improvement in survival estimation was most pronounced for prostate cancer. Where period estimates did not match the eventually observed value, they were predominantly on the lower side. Complete analysis estimates were generally observed to be in between the cohort and period values.
The period method of survival analysis provides more up-to-date estimates of 5-year survival than do traditional cohort-based methods.
We evaluated the use of coronary angiography and clinical outcomes among patients who had heart failure and were enrolled in the Intravenous Novel Plasminogen Activator (NPA) for the Treatment of Infarcting Myocardium Early study, a large international trial of fibrinolytic therapy in ST-elevation myocardial infarction.
Although apolipoprotein E (ApoE) polymorphism is associated with variable risks of several illnesses, and with mortality, no persuasive relationship has been demonstrated with frailty. Here, the clinical examination cohort (n=1452 older adults, aged 70+ years at baseline) of the Canadian Study of Health and Aging was evaluated, with 5-year follow-up data. Frailty was defined using both the phenotypic definition from the Cardiovascular Health Study (Frailty-CHS) and the 'Frailty Index', from which age-specific trajectories of deficit accumulation can be estimated. In age-sex adjusted analyses, people with ApoE 4 allele had a higher risk of death (hazard ratio [HR]=1.20; 95% confidence interval: 1.01-1.45), but this relationship was not significant when adjusted for cognitive impairment (1.06; 95% confidence interval: 0.88-1.27). There was no association between frailty and ApoE polymorphism, defined in age-sex adjusted models either as Frailty-CHS (ApoE4 HR 1.17; 95% confidence interval: 0.98-1.40, frailty HR 1.37; 95% confidence interval: 1.28-1.46) or by the Frailty Index (ApoE4 HR 1.07; 95% confidence interval: 0.90-1.29, frailty HR 35.3; 95% confidence interval: 20.4-61.1). The data do not support an association between ApoE polymorphism and frailty. This result did not depend on how frailty was defined.