BASE Core Study: Design and Sample Description

In total, N = 516 individuals from the western districts of Berlin participated fully in the Intensive Protocol at the first occasion of measurement (representing 27% of the initial verified parent sample of N = 1908 obtained from the city registry). This baseline sample consisted of 258 men and 258 women aged between 70 and 103 years at intake. For age-related comparisons, the sample was divided into six age groups/cohorts (each n = 86): 70-74 years (born 1922-1915), 75-79 years (born 1917-1910), 80-84 years (1913-1905), 85-89 years (born 1908-1900), 90-94 years (1902-1896), and 95-103 years (born 1897-1883). Because of the three-year time interval required for testing, there is some overlap in birth cohort membership across adjacent age groups. For most participants, assessment extended over a period of 3 to 5 months (mean: 4.4 months; range: 1.2-15.4 months) and therefore required major commitment.

An additional N = 412 individuals (22% of the parent sample) completed a 90-minute multidisciplinary Intake Assessment which was collected as the first session of the Intensive Protocol. For ethical reasons, subjects were informed at the outset about the general format and content of the design and their expected involvement. Subjects who were incapable of understanding the purpose and conditions of the study or were evaluated by a psychiatrist or medical doctor as too ill to participate were excluded from the study. Such exclusions concerned about 8% of the verified parent sample. Table 1 provides further demographic information on the BASE Baseline sample of N = 516 participants.

Table 1:

Demographic characteristics of participants of the Berlin Aging Study:
Baseline sample (N = 516; 1990-1993)

Demographic Characteristics | Men N=258 | Women N=258 | Total N=516
Gender (in %) | 50.0 | 50.0 | -
Age (in years) M SD | 84.73 8.44 | 85.11 8.89 | 84.92 8.66
Education (in %) primary lower secondary higher secondary other Missings | 60.9 22.5 11.6 3.9 1.2 | 67.1 24.4 3.5 4.7 0.4 | 64.0 23.4 7.6 4.3 0.8
Occupational training (in %) Missings | 74.8 - | 41.9 0.4 | 58.3 0.2
Income1 (in %) < 1.000 DM 1.000 - 1.399 DM 1.400 - 1.799 DM 1.800 - 2.199 DM > 2.200 DM Missings M (in DM) SD (in DM) | 6.2 17.8 14.7 21.3 32.2 7.8 2172.34 1309.64 | 7.4 17.4 17.1 21.7 17.8 18.6 1778.73 778.35 | 6.8 17.6 15.9 21.5 25.0 13.2 1987.84 1109.64
Marital status (in %) married widowed divorced single | 52.3 39.9 4.3 3.5 | 7.4 69.8 10.5 12.4 | 29.8 54.8 7.4 7.9
Type of residence (%) living alone living with others institutionalized | 36.8 53.5 9.7 | 65.1 17.1 17.8 | 51.0 35.3 13.7

Note: 1 Unweighted data.

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