THE ACCURACY AND COMPLETENESS OF CHILDHOOD-CANCER REGISTRATION IN NEW-ZEALAND

The New Zealand Cancer Registry (NZCR) is the main source of data on c ancer incidence in New Zealand. The accuracy and completeness of regis tration of childhood cancers (ages zero to 14 years) were assessed dur ing the conduct of a case-control study. Newly diagnosed children (199 0-93) were ascertained from three sources: the NZCR; the Patient Manag ement System (hospital admissions and discharges); and the separate Ch ildren's Cancer Registry Pathology reviews were conducted to verify th e diagnoses. Capture-recapture methods were used to assess the complet eness of ascertainment. During the four-year period, 409 incident case s of childhood cancer were confirmed, giving an age-standardized incid ence rate of 131 per million person-years (95 percent confidence inter val = 119-144), The NZCR ascertained 395 (97 percent) of these childre n, In addition, the NZCR notified us of 43 other 'childhood cancer' re gistrations which were not confirmed as new cases of childhood cancer according to our eligibility criteria, The main reasons for these were coding errors (20 registrations), duplicates (seven), and a change in the pathological diagnosis as a result of the pathology review (seven ), The capture-recapture estimate of the total number of incident case s was 410. Overall, the NZCR had good completeness for childhood cance rs, but the number of unconfirmed registrations was larger than expect ed.