Prevalence of Post Mastectomy Pain Syndrome at Kenyatta National Hospital

Abstract

Background: Post mastectomy pain syndrome (PMPS) is a common complication after mastectomy. This is pain persisting 2 to 3 months after mastectomy or any other type of breast surgery is performed. Post mastectomy pain remains a difficult to treat condition once it sets in, with significant consequences for the individual patient’s quality of life and cost of healthcare to society as a whole. A detailed description of PMPS would enable understanding of the magnitude of this problem and development of more effective pain management strategies at our institution. .Objective: The objectives of this study were to determine the prevalence of PMPS in patients undergoing mastectomy at KNH, as well as to determine any predictive factors for the development of PMPS. We also sort to establish any association between intensity of acute post surgical pain after mastectomy and development of post mastectomy pain syndrome. Materials and Methods: This research was conducted as a prospective observational study after getting ethical approval from the Kenyatta National Hospital-University of Nairobi Ethics and research committee. 65 patients who underwent mastectomy at KNH between January 2016 and November 2016 were recruited using a consecutive sampling technique and followed up to 3 months post surgery using a telephone based interview. A modified data collecting tool comprising the Visual analogue scale (VAS) and Douleur neuropathique four (DN4) was used to collect data via telephone at 1 and 3 months post mastectomy for each of the patients. Collected data was analyzed using SPSS version 20. Descriptive statistics was used to determine the prevalence of PMPS. Regression analysis was undertaken to determine the influence of various independent variables on development of neuropathic pain. A paired sample t-test was run to determine association between intensity of acute post surgical pain after mastectomy and development of persistent post mastectomy pain. Results and discussion: Results from 62 (95%) of patients was collected and analyzed. Majority of patients were between 61 and 80 years (50%), were married (48%) and underwent modified radical mastectomy (90%). Analgesic technique employed during mastectomy included an opioid with paracetamol with or without an NSAID (70%). Few patients received in addition a local anesthetic infiltration (13%). On first post operative day 50% reported moderate pain passively that increased to severe with active movement of ipsilateral upper limb. The prevalence of post mastectomy pain syndrome at 3 months was 48%. Neuropathic pain at 1 month was greater at 61%. The results of the paired t-test carried out to find any association between acute pain post mastectomy and development of neuropathic pain showed the difference in means of pain intensity acutely post operatively (both passive and dynamic) and development of neuropathic pain at 1 and 3 months was statistically significant (p value 0.013). Conclusion: Even with less invasive surgeries, PMPS remains a clinically significant problem. There is a significant association between control of acute post operative pain and development of neuropathic pain after mastectomy. Analgesic modalities utilized at our institution are devoid of adjuvant medication or regional analgesic techniques which might explain the poor acute post operative pain control and high PMPS prevalence. Key words: Post mastectomy pain syndrome, prospective observational study, telephone based interview, regression and correlation analysis