Olli P. Heinonen’s research while affiliated with University of Kuopio and other places

Abstract Nationwide and regional participation in the newly started public dental care system, occurrence of caries and proportion of children registered to be in need of restorative treatment during 1974–1979 were studied in 3-5-year-old Finnish children. The data were collected from the annual reports of municipal dental health centers. The mean annual proportion of children participating in the care increased from 27% in 1974 to 71 % in 1979. A clear improvement was noticed in each county, especially in areas where the earlier situation was poor. During the study period an average proportion of entirely caries free children increased from 24% at the beginning lo 57% at the end of the study. The mean annual proportion of children recorded to be in need of restorative care decreased from 61% at the beginning to 32% at the end of the study period. The mean dmft value decreased from 3.7 in 1974 to 1.7 in 1979. A strong inverse relationship existed between the dental health at the beginning of the study period and the extent of changes in dental health during the 6-year-period. Thus regional differences have greatly diminished since the introduction of the public dental care system.

Reproducibility of the skin prick method of testing for allergy was studied in 20 subjects examined by four nurses. Hypodermic needles were used for pricking and the test panel included a histamine control, a diluent control, and nine allergens. The reproducibility of the method was best when the size of the weal reaction caused by an allergen was expressed as the geometric area of the weal. When the weal reaction was expressed as the ratio of the weal reaction caused by an allergen to that caused by histamine, the reproducibility of the method was decreased considerably. When the ratios were further classified into three class ratings, reproducibility was very low. The reduction in reproducibility was due to the low reproducibility of histamine reactions. According to these results, at least in epidemiological studies the weal reactions should be expressed as geometric areas. In clinical practice it might also be preferable to express prick test results as the diameters of the weals without adjusting them by histamine reactions.

The aim was to test the hypothesis that atopy increases the occurrence of chronic bronchitis. Relations between atopy, smoking, and chronic bronchitis were studied in farmers. The data were from two successive postal surveys and a skin prick tested subsample. The cross-sectional study consisted of 9017 farmers. Those 6899 farmers who did not have chronic bronchitis at the beginning and who continued farming were followed for three years. A sample of 150 farmers was skin-tested with 36 allergens. The prevalence of chronic bronchitis (rate per 1000), standardised for age and sex, was 41 in non-atopic non-smokers, 101 in atopic non-smokers, 106 in non-atopic smokers, and 257 in atopic smokers (effect of atopy: p less than 0.001; effect of smoking: p less than 0.001). The standardised incidence rates of chronic bronchitis (per 1000 farming years) were 14, 34, 36, and 50, respectively (atopy: p less than 0.001; smoking p less than 0.001). The relative risk of chronic bronchitis, calculated from the incidence data adjusting for the effects of age, sex, smoking or atopy by logistic regression analysis was 2.2 for atopy (95% confidence interval 1.8-2.7) and 2.3 for smoking (1.8-2.9). Only 20 farmers had chronic bronchitis in the skin-tested subjects; the results were consistent with the findings in the surveys but did not reach statistical significance for atopy. In conclusion, atopy and smoking have independent and additive effects on the occurrence of chronic bronchitis at least in dusty farming work.

The relative importance of associations between caries occurrence and exposure to sugar-sweetened products, fluoride preventives, medication with drugs affecting saliva secretion and the standard of oral hygiene was assessed in 125 mentally retarded and 79 healthy 9-10-yr-old Finnish children. The evaluation of the relative importance of the associations was based on logistic regression analyses. For the mentally retarded children the most important determinant of caries risk was their poor standard of oral hygiene. Frequent use of sugar-sweetened snacks was found to be an important determinant of caries risk for both the mentally retarded and the healthy children.

In Finland, data about the incidence of clinically confirmed (according to predefined criteria) farmer's lung have been collected in successive years since 1980. All special hospitals for pulmonary diseases and departments of pulmonary diseases in other hospitals (23 clinical units throughout Finland) took part in the study. This report deals with the results collected from 1980 to 1982 (inclusive), during which 512 new cases of farmer's lung were recorded, 186 in 1980, 153 in 1981, and 173 in 1982. The mean age of the patients was 47 years (range 14-75), 45 years for men and 48 years for women. About two-thirds of the patients were women. The mean annual incidence of farmer's lung among the entire farming population (standardized for age and sex to the total population in Finland in 1975) was 44 per 100,000 persons in farming. Both the standardized mean annual incidence (range 8-60 per 100,000 persons in farming) and the female/male ratio of the standardized incidence showed distinct regional differences. Most cases of farmer's lung occurred during the indoor feeding season for cattle. The highest frequency of new cases was observed in April and the lowest in October. The incidence of farmer's lung was positively correlated with measures of daily rainfall and negatively correlated with days without rainfall and with sunshine during the haymaking period preceding the diagnosis. A rainy haymaking period calls for artificial drying of hay in order to reduce the incidence of farmer's lung.

Development of chronic bronchitis has been shown to depend strongly on smoking habits. Atopy is known to predispose individuals to the development of asthma. Few studies, however, have dealt with the role of the atopic status of the individual as a predisposing factor for chronic bronchitis. In our previous survey among farmers, we observed that chronic bronchitis occurred more often among atopic than non-atopic subjects. Atopy was defined on the basis of past or present atopic manifestations. The association between atopy and chronic bronchitis was re-examined in a separate study of 169 individuals. Using the skin-prick technique we tested these farmers for atopy. The antigen panel included 36 common and farm-related allergens. Among non-smokers with negative skin tests the prevalence of chronic bronchitis was 5.6%, whereas among farmers with positive skin tests (area of at least one skin test reaction equal to 6 mm2 or larger) the prevalence of chronic bronchitis was 15.1%. When age, sex and smoking habits were accounted for statistically, individuals with positive skin tests suffered from chronic bronchitis twice as frequently as subjects with negative skin tests. The predisposing effects of smoking and atopy were of the same order of magnitude. The results of the clinical study of atopy correspond closely to those of the survey study. In the farming population, individuals with an atopic constitution are predisposed to development of chronic bronchitis.

In order to compare the prevalences of common allergic symptoms identical postal questionnaires were sent to all farmers of a rural municipality in eastern Finland and to a sample of similar size in the adjacent industrialized urban municipality. To investigate the validity of the survey random subsamples of each study group participated in health examinations. In both the rural and urban populations subjects most frequently suffered from allergic rhinitis, 26.7% and 28.8%, respectively of the two populations. The proportions of individuals with any one of the five allergic symptoms recorded did not differ significantly in the two populations. Asthma was somewhat more frequent among the urban than among the rural population. The difference was not statistically significant, however, and could be due to the difference in smoking habits. The factors reported to provoke allergic symptoms were significantly different in the two groups. In the rural population the provoking factors were mostly work-related, whereas in the urban population these factors were related to living conditions.

The levels of circulating IgG antibodies to Aspergillus umbrosus, Aspergillus fumigatus, Thermoactinomyces vulgaris, and Micropolyspora faeni were determined by enzyme immunoassay in 197 subjects selected for a study of farmer's lung (FL). The material consisted of five study groups: 37 patients with clinically confirmed FL, 31 spouses of the patients, 44 immediate relatives of the patients, 35 immediate relatives of the patients' spouses, and 50 unrelated people who were spouses of the 79 people in both relative groups. The mean titres of IgG antibodies to all four microbes were highest in patients with clinically established FL. In the other groups the mean titre of Aspergillus umbrosus, a mould found much more frequently in Finnish farm environments than other moulds under study, was significantly higher (p less than 0.01) in the relatives of FL patients than in other people. This finding remained irrespective of whether the subjects had suffered from FL symptoms or not or whether they worked or lived on the same farm as the patient or on a different one. The difference in the mean titre was not due to the differences between the study groups in age, sex, smoking habits, atopic background, frequency of handling of plant materials, or time interval from the most recent handling of visibly mouldy hay. The results imply that genetic factors may be important in the IgG antibody response to microbial antigens associated with FL.

Of the 373 stroke patients 95 were admitted to the feasibility study of stroke rehabilitation. The patients were divided into two groups, an intensive and a normal treatment group. In this study, the functional recovery of stroke, measured by ADL and motor function was significantly better in the intensive treatment group. There was no difference in institutionalization or incidence of death between the groups. The gain of ADL and motor function was greatest during the first three months after stroke in the intensive treatment group. The conclusion is that intensified physiotherapy seems to improve the functional recovery of stroke patients.