Kosaku Aoyagi1, Laura Frey-Law2, Gabriela Rabasa3, Cora E. Lewis4, Michael Nevitt5 and Tuhina Neogi6, 1Boston University, Quincy, MA, 2University of Iowa, Iowa City, IA, 3Boston University, Boston, MA, 4University of Alabama at Birmingham, Birmingham, AL, 5University of California at San Francisco, Orinda, CA, 6Boston University School of Medicine, Boston, MA
Background/Purpose: PainDETECT has been used in studies of knee OA to identify "neuropathic-like pain", though neuropathic lesions have not been identified in clinical knee OA. PainDETECT, however, is also associated with measures of pain sensitization. Unpredictable knee pain is another type of pain experienced in knee OA that is emotionally draining and has negative impacts on quality of life. Unpredictable pain has been poorly correlated with other pain experiences in knee OA, such as intermittent or constant pain, or pain severity. This suggests that unpredictable pain may reflect a different construct. Whether PainDETECT and unpredictable pain reflect similar underlying mechanisms of altered nociceptive functioning is not known. Therefore, we sought to determine the association between PainDETECT and unpredictable pain in people with knee OA.
Methods: We included participants from the Multicenter Osteoarthritis (MOST) Study, a NIH-funded longitudinal cohort study of persons with or at risk of knee OA. PainDETECT was dichotomized at >12 to reflect possible or probable neuropathic-like pain in knee OA. We evaluated unpredictable pain using a single standalone question from the Intermittent and Constant Osteoarthritis Pain (ICOAP) questionnaire: "How often does your knee pain that comes and goes come on without warning?" with five levels of response from never (0) to very often (4). We defined presence of unpredictable pain as occurring at least "often". We evaluated the cross-sectional relation of having a PainDETECT score >12 to presence of unpredictable pain using knee-based logistic regression with the generalized estimating equation to account for correlations between the knees within an individual, adjusting for age, sex, BMI, race, catastrophizing, and depressive symptoms.
Results: We included 1998 participants (3984 knees) (mean age 66.8 ± 11.2, 58.1% female, mean BMI 29.5 ± 5.7). Of those, 10.6% had a PainDETECT score >12 and 9.3% had unpredictable pain (present "at least often"). Participants with a PainDETECT score >12 had 3-fold greater likelihood of having unpredictable pain compared with those whose score was ≤12 (adjusted odds ratio: 3.14, 95% CI 2.19, 4.49).
Conclusion: PainDETECT scores above the threshold typically used to define possible or probable 'neuropathic-like pain' was associated with unpredictable pain, suggesting a common underlying involvement of the altered nociceptive pathways contributing to distressing pain symptoms in people with knee OA. This study highlights the importance of targeting altered functioning of nociceptive pathways to address unpredictable pain and improve the quality of life in people with knee OA.
Disclosures: K. Aoyagi, None; L. Frey-Law, None; G. Rabasa, None; C. Lewis, None; M. Nevitt, None; T. Neogi, Novartis, Pfizer/Lilly, Regeneron.
