Epidemiology of Upper Limb Complex Regional Pain Syndrome in a Retrospective Cohort of Persons Aged 9-30 Years, 2002-2017.

Introduction This paper describes the epidemiology and clinical presentation of complex regional pain syndrome (CRPS) in a large, integrated health care delivery system; and CRPS incidence rates (IRs) over a time period spanning human papillomavirus (HPV) vaccine licensure and published case reports of CRPS following HPV vaccination. Methods The authors examined CRPS diagnoses in patients aged 9-30 years between January 2002 and December 2017 using electronic medical records, excluding patients with lower limb diagnoses only. Medical record abstraction and adjudication were conducted to verify diagnoses and describe clinical characteristics. CRPS IRs were calculated for 3 periods: Period 1 (2002-2006: before HPV vaccine licensure), Period 2 (2007-2012: after licensure but before published case reports), and Period 3 (2013-2017: after published case reports). Results A total of 231 individuals received an upper limb or unspecified CRPS diagnosis code during the study period; 113 cases were verified through abstraction and adjudication. Most verified cases (73%) were associated with a clear precipitating event (eg, non-vaccine-related injury, surgical procedure). The authors identified only 1 case in which a practitioner attributed CRPS onset to HPV vaccination. Twenty-five incident cases occurred in Period 1 (IR = 4.35/100,000 person-years (PY), 95% confidence interval (CI) = 2.94-6.44), 42 in Period 2 (IR = 5.94/100,000 PY, 95% CI = 4.39-8.04), and 29 in Period 3 (IR = 4.53/100,000 PY, 95% CI = 3.15-6.52); differences between periods were not statistically significant. Conclusion These data provide a comprehensive assessment of the epidemiology and characteristics of CRPS in children and young adults and provide further reassurance about the safety of HPV vaccination.