BackgroundLymphedema (LE) has been called the forgotten vascular disease, given such scant knowledge about LE-associated comorbidities or causes. Such knowledge of the comorbidities and treatment of LE may assist in diagnostic decisions and health care planning. MethodsTo determine the proportion of LE patients with various LE-associated comorbidities as well as the rate of associated treatment, deidentified Health Insurance Portability and Accountability Act-compliant commercial administrative claims from the Blue Health Intelligence (BHI) research database (165 million Blue Cross Blue Shield members) were queried. We analyzed a BHI study sample of 26,902 patients with LE who had been enrolled with continuous medical benefits for 12 months before and after the index date for the complete years 2012 through 2016. Patients were first identified by comorbidity and then grouped into those receiving no treatment for LE and those receiving any treatment for LE. Any treatment was defined as receiving manual lymphatic drainage, physical therapy, compression garments, or a pneumatic compression device. The purpose of this study was to determine the proportion of LE patients comorbid with various known LE-associated conditions and the treatment rates of LE patients with each comorbidity. ResultsAmong the 84,579,269 BHI patients enrolled during the study window, 81,366 patients were identified with LE. From this LE group, our study focused on the 26,902 patients who were enrolled with continuous medical and pharmacy benefits for 12 months before and after the index date. Among these 26,902 LE patients, breast cancer was the most frequent comorbidity with LE (32.1%), and these patients almost universally received any treatment (94.2%); other cancer types, such as melanoma (2.1%) and prostate cancer (0.7%), were less frequent and received any treatment less often, 75% and 82% of the time, respectively. Venous leg ulcer was the most common non-cancer-linked comorbidity for LE (9.6%), but only 81.7% of venous leg ulcer patients received any treatment for LE. ConclusionsTo our knowledge, this is the largest study to date detailing the comorbidities associated with LE and LE treatment rates within each. Our findings suggest that a sizable proportion of cancer-related LE patients do not receive appropriate treatment. Furthermore, this study highlights the role of advanced venous disease as an LE comorbidity that is frequently untreated and its associated gap in treatment.