OCTO-Twin - Population
Twin pairs were drawn from the Swedish population-based Twin Registry. At the first wave the twins had to be born 1913 or earlier and both partners in the pair had to accept participation. At the first wave 351 twin pairs (149 MZ and 202 like-sex DZ pairs) were investigated (average age 83.57 years; 67% of the sample were female). The two-year longitudinal follow-ups were conducted on all twins alive who agreed to participate, irrespective of twin status. The participation in the 2nd Wave was 235 pairs (568 individuals), in the 3rd wave 144 pairs (430 individuals), in the 4th wave 4 86 pairs (315 individuals), and at the last occasion (wave 5) 43 pairs (222 individuals participated. The initial OCTO-Twin sample was found to be similar to a representative sample of non-twins aged 80 and older (Simmons et al., 1997). Linkages are continuously performed to the Twin Registry/Census register and to the death register for vital status.
Data Collection Event
OCTO-Twin - wave 4
Third follow-up of participant. The number of tested individuals and pairs were 315 and 86 respectively.