Angina pectoris was studied in a representative series of male patients (n = 504) with a first myocardial infarction (MI) surviving the hospital stay. The prevalence of questionnaire angina before MI was 28% and of effort-induced chest pain alone 40%. Of the patients with effort-induced chest pain, 72% retained symptoms also after MI. No correlation with age was found. Three months after and one year after infarction the prevalence of effort-induced chest pain was 55% and 45%, respectively. The patients with effort-induced chest pain before MI had a somewhat more severe clinical course and a significantly higher death rate (15% versus 6%) than those without chest pain.
A random sample of men in the age-group 30-39 years from the general population in Göteborg, Sweden, has been investigated with respect to socioeconomic factors and risk factors for coronary artery disease. The total sample could well be characterized with socioeconomic variables obtained from public registers. All the individuals of the sample were invited to an examination which 68% attended (participants). It was found that those not attending the examination (non-participants) greatly differed from the participants. The non-participants were more often unmarried, and had lower annual incomes and more sickness benefit days. There were more foreigners and more individuals registered for intemperance among the non-participants than the participants. Among the participants the foreigners reported lower physical activity and had higher serum cholesterol than the participating Swedes and individuals registered for intemperance stated a higher tobacco consumption and had higher systolic and diastolic blood pressures than those not registered. This highlights that consideration of factors discriminating participants and non-participants is important for proper estimation of population parameters. The same is true for comparisons between cases and controls recruited from cross-sectional population surveys.
Among 262 women with a first myocardial infarction discharged alive from hospital in Göteborg, Sweden between 1968 and 1977, 161 (61%) were smokers at the time of infarction. Postinfarction smoking was established after three months. In relation to smoking status three months after the infarction, subsequent survival and reinfarction rate were calculated by comparing those who smoked before infarction and later stopped (52%) with those who continued to smoke after the infarction (48%). There were no differences in preinfarction characteristics between quitters and continuing smokers. Women who stopped smoking after the infarction had higher serum enzymes during the acute phase than those who continued to smoke. The cumulative five-year survival rate was 85% among those who stopped smoking compared to 73% among those who continued to smoke (p less than 0.05). No significant difference was found in the cumulative reinfarction rate between the two groups with different smoking habits.
All cases of initial myocardial infarctions (MI) diagnosed among men below age 40 in Göteborg during 1970-1977 have been studied. The cases have been compared with a random sample from the general population in Göteborg with respect to socio-economic factors and conventional risk factors. The MI-cases showed a special socio-economic pattern prior to the infarction and were more often single and of foreign origin, had more previous sickness benefit days and were more often registered for alcohol abuse than contemporaries in the general population. Moreover, the surviving MI-cases were found to be heavily burdened with the conventional risk factors smoking, cholesterolemia and high blood pressure.
All patients under 60 years of age who were discharged from hospital after a first myocardial infarction between 1968 and 1977 in Göteborg were followed for a minimum of 24 months. The patients were unselected, and treatment was standardised. The patients were divided into five two yearly cohorts, and the prognostic comparability and mortality of these cohorts were assessed. There was a reduction in the two year mortality rate after discharge during the 10 year period. Small baseline differences between the cohorts were controlled by multivariate methods, and a subsequent analysis showed that there was a declining trend in mortality between 1968 and 1977. A higher tendency among smokers to give up smoking and a lower prevalence of angina pectoris could explain only part of the reduction in mortality. A small number of patients underwent a coronary bypass operation; the slight increase in the number of operations during the period cannot, however, account for the reduced mortality. Most of the patients in the later cohorts were treated with beta blockers, and this is the most likely explanation for the majority of the decline in mortality.
The mortality and morbidity were assessed during a 2-year follow-up in an acute intervention trial in suspected acute myocardial infarction with metoprolol (a selective beta 1-blocker). On admission to the trial, the 1395 participating patients were randomly allocated to metoprolol or placebo for 3 months. Thereafter, if there was no contraindication, patients with infarction and/or angina pectoris were continued on metoprolol for 2 years. A lower mortality was observed after 3 months in patients randomised to metoprolol. The difference remained after 2 years. The difference in 2-year mortality rate was restricted to patients randomised early after onset of pain. Late infarction was observed more often in the placebo group during the first 3 months. When the two groups thereafter were treated similarly, the difference successively declined and did not remain after 2 years. A similar incidence of angina pectoris was observed in the two groups at each check up. During the early recovery period, more patients in the metoprolol group returned to work. No such difference was observed later on.
The relationship of low-back pain (LBP) to other diseases and to cardiovascular risk factors was studied in a random sample of 940 men from 40 to 47 years of age. The life-time incidence of LBP was 61%, the prevalence 31%. The prevalence of other diseases was the same as in previous studies in the same region. In a univariate analysis nine variables were found to be correlated to LBP; angina pectoris, calf pain, breathlessness on exertion, smoking, physical activity at work and during leisure time, worry and tension, fatigue at the end of the workday, and perception of stress. When the influence of other variables was assessed by analysis of covariance, four of the variables maintained a direct association with LBP, viz, calf pain on exertion, smoking, a high physical activity at work, and a frequent feeling of worry and tension.