1. 2017;20;E661-E671High Body Mass Index Is a Potential Risk Factor for Persistent Postoperative Pain after Breast Cancer Treatment
   Retrospective Study
   Noud van Helmond, MD, Hans Timmerman, MSc, Nick T. van Dasselaar, MD, PhD, Carmen C. van de Pol, MD, Soren S. Olesen, MD, PhD, Asbjorn M. Drewes, MD, PhD, Kris Vissers, MD, PhD, Oliver H. Wilder-Smith, MD, PhD, and Monique Steegers, MD, PhD.

BACKGROUND: Risk factors associated with persistent pain after breast cancer treatment are needed to develop prevention and treatment strategies to improve the quality of life for patients with breast cancer.

OBJECTIVES: To identify factors associated with persistent pain in women undergoing breast cancer treatments.

STUDY DESIGN: Retrospective study.

SETTING: Regional hospital in the Netherlands.

METHODS: The primary outcome was pain associated with surgery at more than 6 months postoperatively and patients were stratified based on the associated visual analog” scale score they reported: reporting no pain as “no pain,” pain 1 – 29 mm as “mild pain,” and pain 30 – 100 mm as “moderate/severe pain.” Secondary outcomes were function, symptom, and total quality of life scores. Predefined risk factors analyzed for association with outcomes included: age, smoking status, diabetes, body mass index (BMI), disease stage, surgery type, axillary lymph node dissection, reoperation, chemotherapy, radiotherapy, and hormone therapy.

RESULTS: Of the 718 patients who were approached, 492 were included (follow-up 2.5 ± 1.8 years). Thirty-five percent of patients developed persistent pain (n = 122 “mild pain,” n = 53 “moderate/severe pain’”). Age, BMI, surgery type, axillary lymph node dissection, disease stage, reoperation, chemotherapy, and radiotherapy were identified as potential risk factors in univariate ordinal regression analyses (P < 0.10). Age (P < 0.01) and BMI (P = 0.04) remained independently predictive in the multivariate model. BMI and age were associated with odds ratios (ORs) of 1.04 (95% confidence intervals (CI): 1.00 – 1.08) and 0.97 (95% CI: 0.95 – 0.99), respectively per point and year increase. BMI was associated with a higher symptom score (r = 0.14, P < 0.01), a lower level of function (r = -0.11, P = 0.01), and lower total quality of life scores (r = -0.13, P < 0.01).

LIMITATIONS: The retrospective nature of this study makes it prone to response and misclassification bias.

CONCLUSIONS: BMI and age may be risk factors for persistent postoperative pain after breast cancer treatment.

KEY WORDS: Persistent postsurgical pain, breast cancer treatment, BMI, age, chronic postoperative pain, breast cancer surgery