‘Just give me the best quality of life questionnaire’: the Karnofsky scale and the history of quality of life measurements in cancer trials

OBJECTIVES: To use the history of the Karnofsky Performance Scale as a case study illustrating the emergence of interest in the measurement and standardisation of quality of life; to understand the origins of current-day practices. METHODS: Articles referring to the Karnofsky scale and quality of life measurements published from the 1940s to the 1990s were identified by searching databases and screening journals, and analysed using close-reading techniques. Secondary literature was consulted to understand the context in which articles were written. RESULTS: The Karnofsky scale was devised for a different purpose than measuring quality of life: as a standardisation device that helped quantify effects of chemotherapeutic agents less easily measurable than survival time. Interest in measuring quality of life only emerged around 1970. DISCUSSION: When quality of life measurements were increasingly widely discussed in the medical press from the late 1970s onwards, a consensus emerged that the Karnofsky scale was not a very good tool. More sophisticated approaches were developed, but Karnofsky continued to be used. I argue that the scale provided a quick and simple, approximate assessment of the ‘soft’ effects of treatment by physicians, overlapping but not identical with quality of life.