The Mental Adjustment to Cancer (MAC) Scale: replication and refinement in632 breast cancer patients

Background. Assessment of adjustment of patients in cancer treatment trials is becoming more common and increasingly regarded as a useful outcome meas ure. The widely used Mental Adjustment to Cancer (MAC) Scale was designed t o measure Fighting Spirit (FS), Anxious Preoccupation (AP), Helpless-hopele ssness (HH) and Fatalism. Methods. Questionnaire responses from 632 breast cancer patients were rando mly divided into two groups, one for exploratory analyses and possible scal e refinement, and the other for validation purposes. Results. Estimates of reliability (Cronbach's alpha) were satisfactory for two scales, FS (alpha = 0.85) and HH (alpha = 0.81), but lower for AP (alph a = 0.65) and Fatalism (alpha = 0.64). Exploratory factor analysis suggeste d that the MAC Scale might be measuring six independent constructs includin g two related to Fighting Spirit (Positive Orientation to the Illness, Mini mizing the Illness), two related to Fatalism (Fatalism-revised, Loss of Con trol), a construct we have named Angst, and an unchanged HH construct. Scal es developed to measure these constructs were satisfactorily replicated in confirmatory analyses but some reliabilities were lower than desirable. The general structure of the MAC Scale remained little changed despite the div ision of two scales and the suggested removal of six items. The refined sca les correlated with the Hospital Anxiety and Depression scale and the Medic al Coping Modes Questionnaire, indicating good concurrent validity. Conclusions. While reasonable reliability of the original scales persists t hrough analyses of the MAC Scale, the original factor structure could not b e reproduced. Six refined constructs with strong construct validity were id entified within the overall domain of mental adjustment to cancer.