Neuropathic pain symptoms on the modified painDETECT correlate with signs of central sensitization in knee osteoarthritis.

OBJECTIVE: Clinical tools are needed to identify and target a neuropathic-like phenotype, which may be associated with central sensitization (CS), in osteoarthritis (OA). The modified painDETECT questionnaire (mPD-Q) has face and content validity for identifying neuropathic-like symptoms in knee OA. To further validate the mPD-Q, this study assessed the unknown relationship between mPD-Q scores and signs of CS on quantitative sensory testing (QST) in knee OA. DESIGN: 36 Individuals were recruited with chronic, symptomatic, knee OA without other pain/neurological conditions. Reference QST data were obtained from 18 controls/32 eligible knees, enabling identification of sensory abnormalities/CS among case knees. A standardized questionnaire assessed psychological factors (depressive symptoms and pain catastrophizing), and for individual knees, mPD-Q and pain intensity scores. A standardized/comprehensive QST protocol was conducted for each knee. QST signs of CS were defined as: mechanical hyperalgesia and/or enhanced temporal summation and/or allodynia. The relationship between the presence of CS (yes/no) and a pre-selected mPD-Q score (≤12 or >12), by knees, was assessed using generalized estimating equations. RESULTS: Among 57 eligible case knees, 45.6% had ≥1 sign of CS. Controlling for age, knees with higher mPD-Q scores (>12.0) had higher odds of having QST signs of CS (adjusted odds ratio (OR) = 5.6; 95% confidence interval (CI), 1.3-22.9). This relationship was unaffected by controlling for depression and pain intensity, but was attenuated by pain catastrophizing. CONCLUSIONS: Among painful OA knees, higher mPD-Q scores were associated with greater odds of having signs of CS. Thus, the mPD-Q may aid the identification of CS in people with chronic knee OA.

Neuropathic pain symptoms in a community knee OA cohort.

OBJECTIVE: A neuropathic pain (NP) questionnaire may facilitate the identification of a neuropathic component to osteoarthritis (OA) pain. An existing questionnaire, the painDETECT, was modified for use in knee OA and administered to measure the prevalence and correlates of NP symptoms among adults with this condition. METHOD: Sensibility of the modified painDETECT (mPD-Q) was assessed in 20 OA subjects followed by mail administration in an established knee OA cohort. NP symptoms were defined using a previously established, painDETECT cut-point. Correlates of NP symptoms, including OA severity (Western Ontario and McMaster Universities Osteoarthritis Index, Von Korff Chronic Pain Grade pain subscale score), psychological factors (Centre for Epidemiological Studies Depression Scale, Pain Catastrophizing Scale), and concomitant medical conditions, were evaluated using logistic regression. Construct validity of the mPD-Q was evaluated through co-administration with another NP questionnaire (S-LANSS). RESULTS: The mPD-Q had face and content validity. Of 259 eligible cohort members, 171 (66%) completed the questionnaire; 28% had NP symptoms on the mPD-Q (19% among those without neurological conditions). Independent correlates of NP symptoms were: pain intensity (adjusted odds ratio [OR]=2.1 per 10 unit increase, P<0.0001), the presence of referred back/hip pain (adjusted OR=2.9, P=0.024), number of painful joints (OR=1.2, P=0.20) and one or more self-reported neurological condition (OR=3.0, P=0.026). CONCLUSIONS: Among older adults with chronic symptomatic knee OA, over one-quarter had NP symptoms localized to their knees using the mPD-Q. The mPD-Q may facilitate the identification of a neuropathic component to pain in adults with knee OA who may benefit from further evaluation and/or treatment for NP.