Statistical analysis of longitudinal quality of life data with missing measurements Authors
Received: 12 March 1992 Accepted: 10 April 1992 DOI:
Cite this article as: Zwinderman, A.H. Qual Life Res (1992) 1: 219. doi:10.1007/BF00635621 Abstract
The statistical analysis of longitudinal quality of life data in the presence of missing data is discussed. In cancer trials missing data are generated due to the fact that patients die, drop out, or are censored. These missing data are problematic in the monitoring of the quality of life during the trial. However, by means of assuming that the cause of the missing data lies in the observed history of the patients and not in their unobserved future, the missing data are ignorable. Consequently, all available data can be used to estimate quality of life change patterns with time. The computations that are required are illustrated with real quality of life data and three commonly used computer packages for statistical analysis.
Key words Longitudinal analysis missing data quality of life
Paper read at meeting of the EORTC Quality of Life Study Group, November 1991, Leicester, UK.
This research was supported by a grant from the Dutch Science Foundation (NWO).
EORTC Study Group on Quality of Life. The EORTC core quality of life questionnaire: interim results of an international field study. In: Osoba D, ed.
Effect of Cancer on Quality of Life. Boca Raton: CRC Press Inc, 1991: 185–203.
van Knippenberg FCE, de Haes JCJM. Measuring the quality of life of cancer patients: psychometric properties of instruments.
J Clin Epidemiol 1988; 41: 1043–1055.
Schumacher M, Olschewski M, Schulgen G. Assessment of quality of life in clinical trials.
Stat Med 1991; 10: 1915–1930.
Psychometric theory. New York: McGraw-Hill, 1967.
Applications of item response theory to practical testing problems. Hillsdale NJ: Lawrence Erlbaum, 1980.
Zwinderman AH. The measurement of change of quality of life in clinical trials.
Stat Med 1990; 9: 931–942.
van Holten-Verzantvoort AT, Bijvoet OLM, Cleton FJ, et al. Reduced morbidity from skeletal metastases in breast cancer patients during long-term bisphosphonate (APD) treatment.
Lancet 1987; ii: 983–985.
van Holten-Verzantvoort ATM, Zwinderman AH, Aaronson NK, et al. The effect of supportive pamidronate treatment on aspects of quality of life of patients with advanced breast cancer.
Eur J Cancer 1991; 27: 544–549.
Little RJA, Rubin DB.
Statistical analysis with missing data. New York: Wiley, 1988.
Statistical principles in experimental design. New York: McGraw-Hill, 1971.
SPSS Advanced Statistics User's Guide. Chicago, IL: SPSS Inc, 1990.
SAS Institute Inc.
SAS/STAT User's Guide, Version 6, 4th edition, Volume 2. Cary NC: SAS Institute Inc, 1989.
Dixon WJ, ed.
BMDP, Statistical Software Manual, Volume 2. Berkeley: University of California Press, 1990.
Gelber RD, Goldhirsch A, Simes RJ, Glasziou P, Castiglione M. Integration of quality-of-life issues into clinical trials of breast cancer. In: Cavalli F, ed.
Endocrine Therapy of Breast Cancer III Heidelberg: Springer, 1989: 781–795. Copyright information
© Rapid Communications of Oxford Ltd 1992