A new approach to combining clinical relevance and statistical significance for evaluation of quality of life changes in the individual patient.
OBJECTIVE
Empirical investigation of formerly proposed criteria for relevant changes of health-related quality of life (QOL) regarding their use for monitoring changes in the individual patient. Suggestion of a new criterion trying to overcome the drawbacks of former criteria.


METHODS
QOL data were collected longitudinally in 160 cancer patients receiving chemotherapy at an oncological outpatient unit, giving rise to a total of 975 QOL assessments. QOL was measured using the European Organization on Research and Treatment of Cancer Quality of Life Core Questionnaire. Several formerly suggested criteria of relevant change (distribution based, anchor based) were compared in terms of both prevalence and statistical significance of the resulting relevant changes.


RESULTS
When considering criteria of relevant change suggested in the literature, high proportions (average: 42.3-48.3%) of reputedly relevant changes were found. The majority of these changes (average: 55.8-62.2%) were statistically insignificant. Combination of an increased threshold for clinical relevance with the concept of statistical significance resulted in a more meaningful change criterion.


CONCLUSIONS
Formerly recommended thresholds of relevant change in QOL appear to be unduly low when focusing on the individual patient. A modified criterion is therefore suggested for this case. However, more research is needed for validation and refinement of the proposed criterion.
Kemmler
G
G
Department of Psychiatry and Psychotherapy, Innsbruck Medical University, Innsbruck, Tyrol 6020, Austria. georg.kemmler@uki.at
Zabernigg
A
A
Gattringer
K
K
Rumpold
G
G
Giesinger
J
J
Sperner-Unterweger
B
B
Holzner
B
B
D000328:Adult; D000368:Aged; D000970:Antineoplastic Agents / Q000627:therapeutic use; D005260:Female; D006305:Health Status Indicators; D006801:Humans; D008137:Longitudinal Studies; D008297:Male; D008875:Middle Aged; D009369:Neoplasms / Q000188:drug therapy / Q000523:psychology / Q000534:rehabilitation*; D011594:Psychometrics; D011788:Quality of Life; D016896:Treatment Outcome; D055815:Young Adult
D000970:Antineoplastic Agents