The results of a systematic review published in Arthritis Research & Therapy suggest that comorbidities are highly prevalent but inadequately researched in individuals with polymyalgia rheumatica (PMR).
Investigators performed a literature search of the MEDLINE, EMBASE, PsycINFO, and CINAHL databases from inception to November 2016 for observational research regarding PMR. Investigators also extracted articles about giant cell arteritis, a condition that co-occurs in 10% to 30% of patients with PMR. Articles were reviewed according to predefined criteria and selected for inclusion based on agreement between 2 independent members of the research team. Following selection for inclusion, studies were assessed for quality using the Newcastle-Ottawa tool.
Of 27,698 articles identified using the search terms, 41 were retained for data extraction. Among these 41 studies, 32 were cohort studies and 9 were case-control studies. Significant variation in study design, comorbidities reported, and populations studied were observed. Seven studies reported an association between PMR diagnosis and subsequent onset of specific cancer types, including leukemia, lymphoma, myeloproliferative disease, and specified solid tumors. However, 9 studies reported either no significant association or a negative association between PMR and cancer.
Additionally, positive associations were observed between PMR diagnosis and stroke, cardiovascular disease, peripheral arterial disease, diverticular disease, and hypothyroidism. Regarding hypothyroidism, 1 study found a relative risk of 3.2 (95% CI, 1.71-5.91) for patients with PMR, although another study found no association. Similarly, some studies had conflicting results on the risk for diverticular disease in those with PMR. Two studies reported a positive association between PMR and overall malignancy rate. Regarding quality assessment, many of the studies achieved high marks for cohort or case selection according to the Newcastle-Ottawa criteria, as well as moderate to high scores for outcome measurement. However, many of the cohort studies (n=18) failed to recruit a comparison group, which limits the generalizability of results. Additionally, 19 studies recruited PMR cases based on hospital discharge data alone, which may be a source of bias given that the majority of patients with PMR receive treatment in primary care alone. High levels of heterogeneity (88% to 100%) among studies also precluded the aggregation of data and calculation of pooled odds and hazard ratios for certain comorbidities.
The results of this systematic review suggest an association between PMR diagnosis and several serious comorbidities. However, significant variation among reviewed studies limit the quantification of these comorbidities. Further research should assess a range of comorbidities among people with PMR in representative populations, with methodologically adequate study design.
Partington R, Helliwell T, Muller S, Sultan AA, Mallen C. Comorbidities in polymyalgia rheumatica: a systematic review. Arthritis Res. Ther. 2018;20(1):258.