A Method for Analyzing Mortality Data Collected in Follow-up Studies

Mortality in affective disorders

BACKGROUND

To investigate the mortality rates in affective disorders due to unnatural and natural causes with respect to illness subtype and social-demographic features.

METHODS

Mortality data were determined from a prospective study of 354 outpatients with affective disorders during a follow-up period of 5 years. Death from natural and unnatural causes was compared to sex- and age-specific expectations in the general population. Standardized mortality rates (SMR) in diagnostic subgroups and the influence of social-demographic features were investigated.

RESULTS

The observed 30 deaths represented nearly three times (SMR, 2.9) the number expected on the basis of age- and sex-standardized reference population rates. Death from natural causes occurred with the same rate as expected (SMR, 1.0), death from unnatural causes was 28.8 times higher than expected. Women with affective disorders had a considerable high risk to die from unnatural causes (SMR, 47.1). A significant excess of unnatural death was found in all subtypes of affective disorders, particularly in recurrent major depressive episodes (SMR, 46.7).

LIMITATIONS

The sample was restricted in size. Therefore subgroup differences and multiple relationships of risk factors could not be analyzed with high statistical power.

CONCLUSIONS

The results corroborate earlier findings of excess mortality in major affective disorders and strengthen the view that suffering from recurrent major depression confers per se an important biological risk for suicide. Natural causes of death in affective disorders are comparable to expectations from reference populations. Social-demographic characteristics may contribute to an additional risk of premature death by suicide, particularly in women.

[The age correction of survival probabilities in cancer studies]

PURPOSE

Survival of elder oncological patients may depend on the tumor disease, on reasons not related to the underlying disease or simply on patient's age. Therefore patient' age has to be taken into account if the objective of an oncological study is the disease-related survival. Basically, there are 3 different approaches: multivariate statistical modelling, estimation of disease-related survival after censoring of cases with cause of death not due to the tumor disease, and consideration of demographical data in the general population.

PATIENTS AND METHODS

Our paper deals with the age correction using the data from the 1986/88 census in Germany. We have written a computer program based on SPSSWIN, which allows an automated age correction. Using clinical data of radiotherapy after surgical therapy of bladder cancer, we illustrate the method.

RESULTS

The estimated 5-year-survival using the age correction was--dependent on patient's age in the sample--10% up to 15% higher than the uncorrected rate. In the whole sample of 333 unselected patients, 5-year-survival was corrected from 47% to 59%. In the normal population adjusted for age- and sex-distribution, the expected survival rate was 80%.

CONCLUSIONS

The age correction has substantial influence on survival analysis of male patients elder than 60 years and female patients elder than 70 years. It should therefore be used in oncological studies investigating long-term survival of patients in these age-groups.

Survival and follow-up after pacemaker implantation: a comparison of patients with sick sinus syndrome, complete heart block, and atrial fibrillation

The number of patients receiving cardiac pacemakers for sick sinus syndrome (SSS) has increased considerably in recent years. The literature has suggested that patients with sick sinus syndrome have a shorter life expectancy with pacemaker therapy than patients with total heart block or atrial fibrillation. We studied the survival rate of 1,049 patients with complete heart block, 592 with sick sinus syndrome and 447 with atrial fibrillation. After 10 years we found a survival rate of 54.5% for patients paced for SSS, 34.4% for those with complete heart block, and 24.7% for those with atrial fibrillation (statistical significance: SSS--heart block: p less than 0.05; SSS--atrial fibrillation: p less than 0.01; heart block--atrial fibrillation: NS). Considering the calculated survival rates of a comparable normal population (i.e., 56.5%; 41.2%; 47.8%), the differences in survival expectancy are even more pronounced (SSS-normal: NS; heart block-normal p less than 0.05; atrial fibrillation-normal: p less than 0.05). For patients with sick sinus syndrome, the life expectancy parallels that of the general population, while that of patients with complete heart block or atrial fibrillation have a life expectancy that is considerably lower.

Coronary artery disease mortality in relatives of hypertriglyceridemic school children: the Muscatine study

From 2655 healthy school children participating in the 1973 and 1975 Muscatine Coronary Risk Factor School surveys, two groups of index cases were selected for a detailed family study of coronary mortality: a group with fasting triglyceride levels greater than the ninetieth percentile on both surveys (n = 75) and a group with triglyceride levels less than the tenth percentile on both surveys (n = 47). Coronary mortality in adult (age 30 years or older) first- and second-degree relatives was not different between the two groups. When the families of the high-triglyceride group was further subdivided based on the cholesterol percentile of the index child, greater coronary mortality was observed in the relatives of index cases with high cholesterol (higher than the seventy-fifth percentile). This study suggests that family members of children with elevated triglyceride and low cholesterol levels do not have excess coronary mortality.