Avoidable deaths and random variation in patients' survival

Random error in the numbers of avoidable deaths among cancer patients has not been considered in earlier studies.

Methods to obtain valid confidence intervals (CIs) for numbers of avoidable deaths were developed. The excess mortality rates were estimated for patients diagnosed with colon cancer in five cancer control regions in Finland during 2000-2007 using a relative survival regression model. Numbers of avoidable deaths due to colon cancer and other causes, respectively, were estimated in different scenarios.

Altogether, 4139 and 1335 out of 10 772 patients under 90 years at diagnosis were estimated to have died due to colon cancer and other causes, respectively, during the first 5 years after diagnosis. If all the patients had shared the relative survival of the largest cancer control region to which the country capital belongs, the estimated number of avoidable deaths would have been 146 (95% CI 3-290).

Random error in numbers of avoidable deaths, often substantial, can be quantified by realistic error margins, based on appropriate statistical methods.