Abstract:
In the wake of a large burden of silicosis and tuberculosis among ex-miners from the
South African gold mining industry, several programmes have been engaged in examining and
compensating those at risk of these diseases. Availability of a database from one such programme, the
Q(h)ubeka Trust, provided an opportunity to examine the accuracy of length of service in predicting
compensable silicosis, and the concordance between self-reported employment and that officially
recorded. Compensable silicosis was determined by expert panels, with ILO profusion ≥1/0 as the
threshold for compensability. Age, officially recorded and self-reported years of service, and years
since first and last service of 3146 claimants for compensable silicosis were analysed. Self-reported
and recorded service were moderately correlated (R = 0.66, 95% confidence interval 0.64–0.68), with a
Bland–Altman plot showing no systematic bias. There was reasonably high agreement with 75% of the
differences being less than two years. Logistic regression and receiver operating characteristic curve
analysis were used to test prediction of compensable silicosis. There was little predictive difference
between length of service on its own and a model adjusting for length of service, age, and years
since last exposure. Predictive accuracy was moderate, with significant potential misclassification.
Twenty percent of claimants with compensable silicosis had a length of service <10 years; in almost
all these claims, the interval between last exposure and the claim was 10 years or more. In conclusion,
self-reported service length in the absence of an official service record could be accepted in claims
with compatible clinical findings. Length of service offers, at best, moderate predictive capability for
silicosis. Relatively short service compensable silicosis, when combined with at least 10 years since
last exposure, was not uncommon.
