Association of Intermittent and Constant Knee Pain Patterns With Knee Pain Severity and With Radiographic Knee Osteoarthritis Duration and Severity

Abstract

Objective To examine the relation of knee pain patterns to pain severity and to radiographic osteoarthritis (OA) severity and duration. Methods The Multicenter Osteoarthritis Study is a longitudinal cohort of older adults with or at risk of knee OA. Participants’ Intermittent and Constant Osteoarthritis Pain (ICOAP) scores were characterized as 1) no intermittent or constant pain, 2) intermittent pain only, 3) constant pain only, and 4) a combination of constant and intermittent pain. Knee pain severity was assessed using the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) pain subscale and a visual analog scale (VAS). Radiographic knee OA (ROA) severity was defined as Kellgren/Lawrence grade ≥2, and ROA duration was defined according to the clinic visit at which ROA was first noted. We assessed the relation of ICOAP pain patterns to knee pain severity, ROA severity, and ROA duration using regression models with generalized estimating equations. Results There were 2,322 participants (mean age 68.8 years, body mass index 31.0 kg/m2, 60% female). Higher ICOAP pain patterns, i.e., a mix of constant and intermittent pain, were associated with greater WOMAC pain severity compared with those patients without either pain pattern (odds ratio [OR] 43.2 [95% confidence interval (95% CI) 26.4–61.3]). Results were similar for the VAS (OR 71.2 [95% CI 45.7–110.9]). Those patients with more severe and longer duration of ROA were more likely to have a mix of constant and intermittent pain compared with those without either pain (OR 3.7 [95% CI 3.1–4.6] and OR 2.9 [95% CI 2.5–3.5], respectively). Conclusion Knee pain patterns are associated with radiographic disease stage and duration, as well as pain severity, highlighting the fact that pain patterns are important for understanding symptomatic disease progression.

Association of Pain Sensitization and Conditioned Pain Modulation to Pain Patterns in Knee Osteoarthritis

“…Using the Intermittent and Constant Osteoarthritis Pain scale (ICOAP), developed in response to the aforementioned qualitative work, we have recently shown that the patterns of intermittent, constant, and constant AE intermittent pain are associated with the duration of disease, worsening pain severity, and radiographic OA, thus supporting the qualitative work on which the scale is based (5). In light of this evidence and our increasing understanding of altered pain signal processing, different pain mechanisms may underlie these qualitative pain patterns and the transitions from one to another.…”

“…Initial psychometric testing of the scale demonstrated good validity and reliability (10). The ICOAP was obtained in a knee-specific manner, inquiring about symptom type and severity over the prior 7 days, following a previously validated method (5,11). ICOAP pain patterns were defined as follows: 1) no intermittent or constant pain, 2) intermittent pain only (of at least mild severity and with a frequency of at least sometimes), 3) constant pain only (of at least mild severity), and 4) a combination of constant and intermittent pain.…”

Day-to-day variability of knee pain and the relationship with physical activity in people with knee osteoarthritis: an observational, feasibility study using consumer smartwatches

“…This was done separately for both the lunchtime and early evening pain; as the patterns of pain were similar, we decided to present only the lunchtime pain scores. In line with previous literature by Carlesso et al who have written extensively about the idea of OA causing two types of pain: intermittent (variable) and constant (stable), 20 we also explored a two-class model (based on variance only), which included constant (stable) pain and intermittent (variable) pain.…”

The Challenges in the Primary Prevention of Osteoarthritis

“…An important aspect to consider when choosing a potential outcome of symptomatic OA is the fact that in early stage OA, pain can be absent for prolonged periods of time, with short and very sudden short flare-ups. 55,56 For patients with early-stage OA, it is this intermittent pain that is extremely burdensome. 57 When pain is highly fluctuating, one can question the clinical relevance of a single measure in time of something like "pain during walking" or the PASS.…”