Are self-report of disability pension and long-term sickness absence accurate?
Self-reported DP data may be very useful in studies when register information is not available, however, register data is preferred especially for LTSA. The same degree of twin similarity was found for truthful self-report of DP and LTSA in both monozygotic and dizygotic twin pairs. Thus, the response style was not influenced by genetic factors. One consequence of this would be that when estimating the relative importance of genetic and environmental effects from twin models, heritability estimates would not be biased.
Available evidence suggests that investigators should consider using a number of retention strategies across several themes to maximize the retention of participants. Further research, including explicit evaluation of the effectiveness of different strategies, is needed.