4.1. Study design and populations

This study is part of a larger epidemiological study of subjects aged 64 years or over in the community of Lieto, Finland. Two consecutive cross-sectional surveys comprising an interview followed by a health examination were conducted. The purpose of the Lieto study was to investigate general illnesses among the elderly, with particular reference to cardiovascular and pulmonary diseases.

The first survey was carried out between October 1990 and December 1991 and the second between March 1998 and September 1999. Persons born in 1926 or before who had been Lieto residents according to Population Register Center on 23.3.1990 (n =  1360) were invited to attend the first study. The invitation to attend the second study was sent to the persons born in 1933 or before who had been Lieto residents according to Population Register Center on 16.2.1998 (n = 1596). The study populations are presented in Fig. 1. The participants were invited to come to the Lieto Health Center in a random order. In 1990–91, 77 subjects died before they could be examined, 68 declined (4 because of relatives), 5 had moved elsewhere, 12 could not be traced, 1 was hospitalized before the study, and 1 failed to turn up. In 1998–99, 63 died before they could be examined, 200 declined, 4 had moved elsewhere, 59 did not respond, and 10 could not be traced. No information was available on those who did not participate (Isoaho 1995, Wendelin-Saarenhovi 2002).

The only exclusion criterion of the present study was living in a long-term institution. The home-dwelling elderly were selected from the population to evaluate their drug use, with the hypothesis that drug use would be more prevalent if institutionalized persons had been included.

In 1990–91, altogether 1196 persons (93% of those eligible) participated, and 1131 (469 men and 662 women) of them were living at home. In 1998–99, altogether 1260 persons participated (82% of those eligible), and 1197 (518 men and 679 women) of them were living at home. The ages of the home-dwelling participants ranged from 64 to 96 years in 1990–91 and from 64 to 97 years in 1998–99. Their mean age was the same in both surveys, 72 years for men (SD 6.3 in 1990–91 and SD 6.2 in 1998–99) and 73 years for women (SD 6.6 in both surveys). The use of psychotropics by the young elderly aged 64–71 years in 1990–91 (n = 573, 46% men) and 1998–99 (n = 583, 46% men) was studied separately, because they were different persons in both surveys.

Lieto is a semi-rural southwestern municipality near the City of Turku in Finland. The living conditions of this population are typical of those prevailing in southern Finland. Previously mainly an agricultural area, Lieto has been transformed since the Second World War into a commuter and partly industrialized community with a growing population. Its population was 12255 in 1990 and 13845 in 1999, with about 10% and 12% of the people aged 65 years or over, respectively, compared to 13% in 1990 and 15% in 1999 in Finland (Central Statistical Office of Finland 1991, Statistics Finland 1998, Statistics Finland 2000). The age distributions of these Lieto elderly populations were similar to those of the whole nation in both surveys. Today, residents of Lieto work in the social service sector, industry, and agriculture in the same proportions as Finns in general (Statistics Finland 2001), but in the late 1980´s, working-aged persons in Lieto held industrial jobs more prevalently than Finns in general (Tilastokeskus 1991).

The municipal Health Center in Lieto provides primary health care for the population. The number of people in institutional long-term care remained stable from the early to the late 1990s. In Lieto, as elsewhere in Finland, most of the physicians working in health centers are general practitioners, and there was no staff turnover between 1990 and 1998–99, with the exception of a couple of new physicians.