Formulae for the variance of the average time to cure were developed to be able to assess the variability of average time to cure in each analysis (see Appendix).
Variance-weighted least squares linear regression was used to evaluate time trends in survival, in the percentage of children cured and in the average time to cure.
In this study, following a sensitivity analysis, average time to cure was defined as the point at which 1% of 'fatal' cases were still alive (De Angelis et al, 1999).
Average time to cure is estimated as the time at which an arbitrary but small proportion of 'fatal' cases is still alive.
Average time to cure increased from 11.0 years (95% confidence interval (CI): 10 12) in children diagnosed during 1971 1975 to 15.9 years (95% CI: 12 21) in children diagnosed during 1986–1990 (average annual increase of 0.2 years; P<0.001).
Average time to cure increased from 12 years (95% confidence interval (CI): 11 14) to 19 years (95% CI: 14 26) for lymphoid leukaemia (average annual increase of 0.3 years; P<0.001), but remained at about 5 years for acute nonlymphoblastic leukaemia.
Data on children diagnosed with leukaemia during 1971 2000 in Great Britain were used to estimate trends in survival, the proportion cured and the average time to cure.
Average time to cure is defined as the time since diagnosis at which the excess mortality rate has declined to or below a predetermined small value.
In contrast to the steady improvement in the percentage cured, the average time at which cure was declared increased most rapidly during the 1980s.
From the time of cure to their expected death, patients with a history of PTB can expect an average of 0.98 QALYs less than the patients in the LTBI group.
