Radiotherapy utilisation in lung cancer in New Zealand: disparities with optimal rates explained.

Background and purpose The intervention rate (IR) of radiotherapy (RT) is important for health service planning. As actual IRs are commonly lower than those predicted by models, we sought to determine the reasons for this discrepancy, using lung cancer in a mixed urban-rural region of New Zealand (NZ). Methods The appropriate utilisation of RT was calculated as the sum of the actual utilisation 3 years post diagnosis (88% of cases deceased), the estimated utilisation of the 12% remaining alive, and the percentage of cases that may have benefited from RT but did not receive it. Results The actual utilisation was estimated as 43% (range 40–48%). A further 8% of deceased cases may have benefitted from RT (but were not referred), giving an appropriate utilisation of 51%. An additional 3.5% that may have benefitted from RT declined management. The difference from modelled IRs was due to a combination of early mortality, refusal of treatment and assumed higher RT treatment rates for many clinical scenarios. Conclusion The appropriate utilisation of RT was substantially lower than IRs derived from models. The assumptions from which these models were derived may result in over-estimates for resource planning purposes. The intervention rate (IR) for radiotherapy (RT) is the proportion of cases that receive RT at any stage during the course of the disease. The IR is important to clinicians, health planners and funders, as it is directly linked to the requirement for high capital cost irradiating equipment and staff. Using evidence-based decision tree models, the “optimal” or “ideal” intervention for lung cancer has been estimated to be 76% in Australia 1 ; 61% in Canada; 2 63% in Scotland 3 and 66% in England, 4,5 but has not been modelled for New Zealand (NZ). Actual IRs also vary widely internationally, often with marked deviation from the modelled rates. The IR for RT in the treatment of lung cancer is unknown in NZ. Lung cancer is the commonest cause of cancer death in NZ. 6,7 It accounts for 9% of all new cancer registrations 6 and about 8% of all cancer patients that receive RT. 8 An audit of the management of lung cancer patients in the Auckland-Northland region of NZ 9-12 provided the opportunity to assess the actual IR for lung cancer and to compare the results with estimates derived from published models. The Auckland-Northland region which has a population of 1.5 million (37% of the NZ population), is serviced by a single regional oncology service. This region is divided into four District Health Boards (DHBs). Those within the greater Auckland urban area are Auckland DHB (ADHB), Counties Manukau DHB (CMDHB) and