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Introduction
The Over 50's study was conducted as a
multi-wave mailout to pairs of twins on the
Australian Twin Registry (ATR) who
were over 50 years of age. In total, 4562 twins (2281 pairs) were recruited
for the survey, of whom 3116 individuals (1279
complete pairs and 558 singles) completed and returned the 16-page
questionnaire form. A further 286 responses were obtained via an abbreviated
two-page telephone questionnaire from twins who refused to complete the full
questionnaire (107 co-twins of singles who completed the full survey, 58 twin
pairs, 63 singles).
The initial database contained 4186 twins
of whom 2353 (1176 pairs + 1 single) were selected for the Wave 1 mailout in November 1993. The selected twins were those
who were not part of Cohort 1, as these were participating in the Semi-Structured Assessment for
the Genetics of Alcoholism (SSAGA) survey at the time. 295 twins from
Wave 1 who refused to fill out the full survey form agreed to answer a
considerably abbreviated telephone survey. Wave 2 occurred in October 1994,
and consisted of 376 new twins appended from the ATR who had turned 50 in the intervening period since
Wave 1, plus the pairs of twins from Cohort 1. However, all Victorian twins
were excluded since the mailout coincided with the
Melbourne SSAGA BLOOD bleeding program. In total 1296 twins (648 pairs) were
selected for this mailout. Wave 3 occurred in July
1995, and consisted of those 864 twins (432 pairs) who were excluded
previously.
49 twins who were present on the Wave 1
list from ATR were absent from the updated Wave 2 list, presumably
due to their death or being marked for deletion in the intervening 12 month
period. Survey forms were not sent to these twins,
however their details remain in the study database.
Questionnaire Contents
- Personal details
- General health
- Personality
- Relationships
- Life events
- Smoking
- Alcohol
- Exercise
- Anxiety and depression
- Bones and joints
- Health conditions checklist
- Vitamins and supplements
- Sun exposure
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