The Effect of Pain on Physical Functioning After Breast Cancer Treatment: Development and Validation of an Assessment Tool.

Objectives: Persistent postsurgical pain, musculoskeletal pain, sensory disturbances, and lymphedema are major clinical problems after treatment for breast cancer. However, there is little evidence on how these sequelae affects physical function. The aim this study was to develop and validate a procedure-specific tool for assessing the impact of pain and other sequelae on physical function after breast cancer treatment.

Methods: A literature review, patient and expert interviews were used to identify dimensions of physical function and sequelae. A questionnaire was developed and tested using cognitive interviews, and field tested among 389 patients treated for primary breast cancer without recurrence (response rate 81%). Median follow-up was 14 months. Using item response theory we identified 5 cause scales of reduced physical functioning: pain after surgery, musculoskeletal pain, sensory disturbances, lymphedema, and other causes. Convergent validity was assessed using the Quick-Dsability of Arm, Shoulder, and Hand Scale (Q-DASH).

Results: About half of the patients reported decreased physical function. All 5 scales displayed good fit, unidimensionality, monotonicity, local independence, and lack of differential item functioning. Cronbach coefficient α ranged from 0.88 (other causes) to 0.96 (sensory disturbances) for the 5 scales. For the Q-DASH α was 0.91. Each scale revealed different information on causes of reduced function.

Discussion: The present scales displayed good psychometric qualities, and may be used to evaluate the impact of specific sequelae after breast cancer treatment on physical functioning, as well as to monitor and target interventions to optimize pain treatment and rehabilitation.