Quality of life in breast cancer patients--a quantile regression analysis.
BACKGROUND
Quality of life study has an important role in health care especially in chronic diseases, in clinical judgment and in medical resources supplying. Statistical tools like linear regression are widely used to assess the predictors of quality of life. But when the response is not normal the results are misleading. The aim of this study is to determine the predictors of quality of life in breast cancer patients, using quantile regression model and compare to linear regression.


METHODS
A cross-sectional study conducted on 119 breast cancer patients that admitted and treated in chemotherapy ward of Namazi hospital in Shiraz. We used QLQ-C30 questionnaire to assessment quality of life in these patients. A quantile regression was employed to assess the assocciated factors and the results were compared to linear regression. All analysis carried out using SAS.


RESULTS
The mean score for the global health status for breast cancer patients was 64.92+/-11.42. Linear regression showed that only grade of tumor, occupational status, menopausal status, financial difficulties and dyspnea were statistically significant. In spite of linear regression, financial difficulties were not significant in quantile regression analysis and dyspnea was only significant for first quartile. Also emotion functioning and duration of disease statistically predicted the QOL score in the third quartile.


CONCLUSIONS
The results have demonstrated that using quantile regression leads to better interpretation and richer inference about predictors of the breast cancer patient quality of life.
Pourhoseingholi
Mohamad Amin
MA
Research Center of Gastroenterology and Liver Diseases, Shahid Beheshti University MC, Tehran, Iran. Aminphg@gmail.com
Safaee
Azadeh
A
Moghimi-Dehkordi
Bijan
B
Zeighami
Bahram
B
Faghihzadeh
Soghrat
S
Tabatabaee
Hamid Reza
HR
Pourhoseingholi
Asma
A
D000222:Adaptation, Physiological; D000223:Adaptation, Psychological; D000328:Adult; D000367:Age Factors; D000368:Aged; D000971:Antineoplastic Combined Chemotherapy Protocols / Q000008:administration & dosage*; D001943:Breast Neoplasms / Q000188:drug therapy* / Q000473:pathology / Q000523:psychology* / Q000601:surgery; D017024:Chemotherapy, Adjuvant; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D007492:Iran; D016014:Linear Models; D011788:Quality of Life; D018570:Risk Assessment; D018434:Sickness Impact Profile; D011795:Surveys and Questionnaires