Waiting time thresholds: are they appropriate?

The introduction of health reforms in New Zealand included the setting of an arbitrary waiting time threshold of 6 months for surgery. The aim of the present study was to investigate the differences in waiting times for different diagnoses in elective general surgery, and the interplay between diagnoses and waiting time thresholds.

A survival curve analysis of 918 patients placed on the elective general surgical waiting lists was conducted. This was undertaken in a tertiary level hospital in New Zealand before the implementation of the waiting time thresholds. The difference between diagnoses of time waited for elective surgery (plotted on survival curves), and hazard function for patients waiting at 180, 360 and 540 days, was investigated.

Survival curves for malignancy, cholelithiasis, hernias and anorectal disease were different on log-rank test (P < 0.001). Those with a diagnosis of malignancy show that at 180 days the hazard function was 0.0049 but by 360 days had dropped to zero. With hernias and anorectal disease, the drop to zero appeared to be delayed until 540 days; however, the confidence intervals at 360 days included zero. In the case of cholelithiasis, the hazard functions indicate surgery occurring until 540 days.

There are different waiting time thresholds for different surgical illnesses. Setting a universal waiting time for elective surgery is not supported.