Long-term Relative Survival Research Articles

Late survival after abdominal aortic aneurysm repair: Influence of coronary artery disease

To evaluate long-term survival in relation to preoperative risk factors, we reviewed 1112 patients undergoing abdominal aortic aneurysm (AAA) repair from 1970 to 1975. A 6-to 12-year follow-up was obtained on 1087 patients (97.7%) by chart review, death certificates, autopsy reports, and questionnaires returned by patients and referring physicians. Preoperatively 24% of patients had a history of prior myocardial infarction, 19.9% had a history of angina, and 40.4% were hypertensive. Emergency operation for ruptured aneurysm was performed in 6.5% and for expanding aneurysm in 3.4% of patients. The survival rate at 5 years was 67.5% and at 10 years was 40.7%. Cardiac-related problems were the most frequent cause of death (38%); 23% died of myocardial infarction and 15% from other heart disease or sudden death. Other causes included neoplasm (14.6%), other ruptured aneurysm (8.2%), and stroke (6.8%). Cause of death was unknown in 19.6%. A significant correlation of reduced survival time was noted in patients with advanced age and those with evidence of heart disease or hypertension. For patients without preoperative evidence of heart disease or hypertension, the 5-year mortality rate from myocardial infarction was 3.7%, compared with 11.7% for those with a positive history of hypertension and heart disease (p = 0.0001). For patients with no preoperative evidence of hypertension or heart disease, the length of survival after AAA repair was the same as that expected for the general population with the same age and sex composition. This study supports the contention that coronary angiography and prophylactic coronary bypass grafting should be performed selectively. Decisions regarding the need for coronary revascularization should be based on symptoms, noninvasive testing, and selective coronary angiography because aneurysmal disease alone is not shown in this study to increase the risk of death from myocardial disease. For patients with clinical findings of coronary artery disease, an aggressive diagnostic approach appears to be justified.

On long-term relative survival rates

The relative survival rate over a given period has been defined as the ratio of the proportion of survivors over the period in the patient group, to the proportion of survivors expected in a similar group of persons without the disease. If there are found consecutive relative survival rates, all calculated from the beginning of follow-up up to points separated by one year, which increase with lengthening of the interval after a specific year, it has been interpreted that the patients are affected by a smaller mortality then expected [2] after that year. An example in this paper demonstrates that this may not necessarily be true, particularly when a long-term follow-up of a heterogeneous patient population with respect to the expected survival is involved. Furthermore, the relative survival rate has been interpreted [1,5] as the proportion of survivors, provided the only disease capable of killing patients is that of the patients. It is also shown that this interpretation is impossible for long-term relative survival rates in a heterogeneous population. If mortality during a specific part of follow-up is of interest in a heterogeneous population, it is suggested that annual relative survival rates be examined instead of drawing a relative survival curve. If the long-term survival due to a specific disease of the patients in a heterogeneous population is desired, methods of the theory of competing risks, and the examination of relative survival curves by age and by other background variables, which make the patient groups homogeneous with respect to the expected survival, are suggested as alternative or auxiliary methods.

What is early diagnosis doing?

Programs for the early detection of cancer in the past have been beset with problems of low yield, inability to recruit high risk populations, poor utilization of physicians, and inadequate end results evaluation. Nevertheless, for twelve forms of cancer representing 80% of all cancers and 70% of all cancer mortality there is a useful form of early detection or prevention. Furthermore, the ultimate benefit of early diagnosis to patients is supported by long-term relative survival rate studies, and for certain forms of cancer by reduction in mortality rates as well. Efforts are now underway to develop risk factor detection programs which will overcome some of the aforementioned problems. One such program is the risk factor analysis project, operating in the CANSCREEN clinics, which was designed to detect high risk indicators for cancer which are amenable to intervention by primary prevention or diagnosis and treatment. A triage system with linkages to comprehensive cancer centers has been established and a medical information system prepared for centralized statistical and epidemiological studies. The clinics are operated entirely by nurse examiners and health educators. Results of pilot studies are encouraging with regard to the feasibility of implementing such programs.

A response-surface approach to the combined effects of temperature and salinity on the larval development of Adula californiensis (Pelecypoda: Mytilidae). II. Long-term Larval survival and growth in relation to respiration

Larvae of the bivalve molluso Adula californiensis (Phillippi, 1847) were reared for 3 days, from fertilization to veliger stage, at optimum conditions (15°C, 32.2‰ S), and then transferred to experimental temperatures and salinities for 22 more days to determine the effects of these factors on survival and growth. For larvae surviving to 25 days, maximum survival was estimated, by response-surface techniques, to occur at temperatures below 10°C and at salinities above 25‰. A comparison of 60% survival response contours for 3, 15 and 25-day old larvae indicated a progressive shift in temperature and salinity tolerance with age of larvae. The older larvae became more tolerant to reduced salinity, but less tolerant to high temperatures. Growth of the larvae over 25 days of culture was slight, and relatively independent of temperature and salinity conditions found in the environment. Oxygen consumption of 3-day old veliger larvae measured at various combinations of temperature and salinity generally increased from 7° to 18°C, and then sharply decreased from 18° to 21°C. A plateau of oxygen consumption from 9° to 15°C at 32.9‰ S indicated that the larvae are adapted to oceanic rather than estuarine conditions. A comparison of 25-day larval survival, mean length, and growth, with oxygen consumption of 3-day old veliger larvae indicated that high temperatures (15°C, and above) coupled with reduced salinities (26.1‰, and below) were unfavorable for prolonged larval life. Because of the lack of larval adaptations to estuarine conditions, larva survival and, hence, successful recruitment of this species within Yaquina Bay (Oregon, USA) depends upon the essentially oceanic conditions found only during the summer in the lower part of the Bay.