Quality of hospital discharge data for injury prevention

Objective: To examine the use of unspecified codes for the circumstances of injury for New Zealand public hospital discharges at a district health board (DHB) level. Methods: Hospital injury discharges for the period 2000-3 were examined. The use of the International Classification of Diseases unspecified categories was examined for mechanism of injury, activity and place of occurrence. Results: For all DHBs, the combined age-adjusted and mechanism-adjusted usage of unspecified mechanism codes was 7% and ranged from 3% to 11%. Most (57%) of these cases were unspecified falls. The comparable usage for activity was 39% and ranged from 17% to 52%, and for place of occurrence the respective figures were 23% and 7-36%. Only 50% of hospital discharges were completely specified in terms of mechanism of injury, activity and place of occurrence; this varied from 36% to 74% between DHBs. For several DHBs a significant degree of inconsistency was found in performance across mechanism, activity and place of occurrence coding. Conclusions: Those DHBs with a high proportion of cases coded as unspecified would serve the prevention efforts of their communities better by making efforts to determine the cause of this situation and implement measures to reduce the problem.