A Structural Equation Model (SEM) for Pharmacist Competencies in Improving Quality of Life of Cancer Patients: Effect of Missing Values on the SEM


Objective: With the goal of improving health-related quality of life (HRQOL) in cancer patients, we previously reported a structural equation model (SEM) of subjected QOL and qualifications of pharmacists, based on a series of questionnaires completed by patients and pharmacists. However, several patients and pharmacists were excluded from the previous study because it was not always possible to obtain all the data intended for collection. In order to reveal the effect of missing data on the SEM, we established SEMs of HRQOL and the competency of pharmacists, using correlation matrices derived by two different statistical methods for handling missing data. Method: Fifteen cancer patients hospitalized for cancer and were receiving opioid analgesics for pain control, and eight pharmacists were enrolled in this study. Each subject was asked four times weekly to answer questions presented in a questionnaire. SEMs were explored using two correlation matrices derived with pair-wise deletion (PD matrix) and list-wise deletion (LD matrix). The final models were statistically evaluated with certain goodness-of-fit criteria. Results: Data were intended to be collected four times weekly for each patient, but there were some missing values. The same SEMs for HRQOL were optimized using both the LD and PD matrices. Although the path diagrams of the SEMs were not identical in the “competency of pharmacists,” the two models suggested that a higher competency of a pharmacist lowered the “severity” of condition and increased the “comfort” of patients, resulting in an increase in the subjected QOL. Conclusion: In collecting data for clinical research, missing values are unavoidable. When the structure of the model was robust enough, the missing data had a minor effect on our SEM of QOL. In QOL research, the LD matrix as well as the PD matrix would be effective, provided the model is sufficiently robust.

Share and Cite:

R. Takehira, K. Murakami, S. Katayama, K. Nishizawa and S. Yamamura, "A Structural Equation Model (SEM) for Pharmacist Competencies in Improving Quality of Life of Cancer Patients: Effect of Missing Values on the SEM," Pharmacology & Pharmacy, Vol. 2 No. 3, 2011, pp. 226-232. doi: 10.4236/pp.2011.23031.

Conflicts of Interest

The authors declare no conflicts of interest.


[1] C. D. Hepler, L. M. Strand, “Opportunities and responsibilities in pharmaceutical care,” Am J Hosp Pharm. Vol. 47, 1990, pp. 533-543.
[2] B. J. Bereznicki, G. M. Peterson, S. L. Jackson, H. Walters, K. Fitzmaurice, P. Gee, “Pharmacist-initiated general practitioner referral of patients with suboptimal asthma management,” Pharm World Sci. Vol. 30, 2008, pp. 869-875.
[3] M. Kamatari, S. Koto, N. Ozawa, C. Urao, Y. Suzuki, E. Akasaka, K. Yanagimoto, K. Sakota, “Factors affecting long-term compliance of osteoporotic patients with bisph- osphonate treatment and QOL assessment in actual practice: alendronate and risedronate,” J Bone Miner Metab. Vol. 25, 2007, pp. 302-309.
[4] P. Gilbar, K. Stefaniuk K, “The role of the pharmacist in palliative care: results of a survey conducted in Australia and Canada,” J Palliat Care. Vol. 18, 2002, pp. 287-92.
[5] World Health Organization: Cancer Pain Relief: With a Guide to Opioid Availability. Second edition, World Health Organization, 1996.
[6] H. Schipper, “Guidelines and caveats for quality of life measurement in clinical practice and research,” Oncology. Vol. 4, 1990, pp. 51-57.
[7] S. Kaasa, J. H. Loge, “Quality of life in palliative care: principles and practice,” Palliat Med. Vol. 17, 2003, pp. 11-20.
[8] J. E. Ware Jr, C. D. Sherbourne, “The MOS 36-item short-form health survey (SF-36). I. Conceptual framework and item selection,” Med Care. Vol. 30, 1992, pp. 473-483.
[9] H. Schipper, J. Clinch, A. McMurray, M. Levitt, “Measuring the quality of life of cancer patients: the functional living index-cancer: development and validation,” J Clin Oncol. Vol. 2, 1984, pp.472-483.
[10] D. F. Cella, D. S. Tulsky, G. Gray, B. Sarafian, E. Linn, A. Bonomi, M. Silberman, S. B. Yellen, P. Winicour, J. Brannon et al. “The functional assessment of cancer therapy scale: development and validation of the general measure,” J Clin Oncol. Vol. 11, 1993, pp.570-579.
[11] W. L. Ward, E. A. Hahn, F. Mo, L. Hernandez, D. S. Tulsky, D. Cella, “Reliability and validity of the Functional Assessment of Cancer Therapy-Colorectal (FACT- C) quality of life instrument,” Qual Life Res. Vol. 8, 1999, pp. 181-195.
[12] M. G. Carson, M. I. Fitch, M. L. Vachon, “Measuring patient outcomes in palliative care: a reliability and validity study of the Support Team Assessment Schedule,” Palliat Med. Vol. 14, 2000, pp. 25-36.
[13] M. Miyashita, K. Matoba, T. Sasahara, Y. Kizawa, M. Maruguchi, M. Abe, M. Kawa, Y. Shima, “Reliability and validity of the Japanese version of the Support Team Assessment Schedule (STAS-J),” Palliat Support Care. Vol. 2, 2004, pp. 379-385.
[14] R. H. Hoyle (Ed), “Structural Equation Modeling: Concepts, Issues, and Applications”. Sage publications, Thou- sand Oaks, California, 1995.
[15] B. M. Byrne, “Structural Equation Modeling With Amos: Basic Concepts, Applications, and Programming (Multivariate Applications Series),” Lawrence Erlbaum Assoc Inc. Publishers, Mahwah, New Jersey, 2001.
[16] C. H. Yeh, “Health-related quality of life in pediatric patients with cancer. A structural equation approach with the Roy adaptation model,” Cancer Nurs. Vol. 25, 2002, pp. 74-80.
[17] K. H. Sousa, F. F. Dhen, “A theoretical approach to measuring quality of life,” J. Nursing. Measurement. Vol. 10, 2002, pp. 47-58.
[18] L. B. Meuleners, A. H. Lee, C. W. Binns, A. Lower, “Quality of life for adolescents: assessing measurement properties using structural equation modeling,” Qual Life Res. Vol. 12, 2003, pp. 283-290.
[19] K. Shimozuma, “Quality of life assessment,” Breast Cancer. Vol. 9, 2002, pp. 100-106.
[20] S. Yamamura, R. Takehira. K. Kawada, S. Katayama, K. Nishizawa, M. Hirano, Y. Momose, “Structural equation modeling of qualification of pharmacists to improve subjected quality of life in cancer patients,” J Pharm Pharm Sci, Vol. 8, 2005, pp. 544-551.

Copyright © 2022 by authors and Scientific Research Publishing Inc.

Creative Commons License

This work and the related PDF file are licensed under a Creative Commons Attribution 4.0 International License.