Musculoskeletal Pain Phenotypes in Private Orthopedic Clinics in Mexico, Including Mixed Pain: A Multicenter Study

Musculoskeletal pain is a leading reason for seeking medical care among adults, with a high prevalence and major impact on quality of life and healthcare systems. Pain can be classified by pathophysiology as nociceptive, neuropathic, nociplastic, and mixed. Although mixed pain is not yet formally recognized by the International Association for the Study of Pain, it is increasingly identified in clinical practice. In Mexico, the distribution of these pain phenotypes in private orthopedic care is unknown.

To estimate the prevalence of operationally classified musculoskeletal pain phenotypes among adults attending private orthopedic clinics in Mexico.

We conducted a multicenter, cross-sectional analytical study involving 6895 patients (> 18 years) from 156 FEMECOT-affiliated private orthopedic clinics across 30 of Mexico's 32 states between January 2023 and April 2024. Pain phenotypes were classified using medical history, physical examination, validated questionnaires (Leeds Assessment of Neuropathic Symptoms and Signs and Brief Pain Inventory), and auxiliary studies when available. Group comparisons were performed using nonparametric tests, and associations were evaluated using multinomial logistic regression, reported as average marginal effects and adjusted for relevant covariates.

Using the study's standardized clinical phenotyping algorithm, the prevalence of operationally classified pain phenotypes was 54% (95% CI 52%-55%) for nociceptive pain, 5.2% (95% CI 4.7%-5.7%) for neuropathic pain, 1.0% (95% CI 0.8%-1.3%) for nociplastic pain, and 39% (95% CI 38%-40%) for mixed pain. Nociplastic pain was more frequent in women and relatively more common in the cervical region. In contrast, nociceptive pain was more prevalent in knee-related conditions, whereas mixed pain was more frequent in patients with chronic pain, particularly in the lumbosacral region.

In this multicenter private-clinic sample, nociceptive pain was the most frequent operationally classified phenotype, and mixed pain represented a substantial proportion of cases. These findings support the need for a comprehensive and individualized diagnostic approach in private orthopedic practice, while warranting cautious interpretation given the use of a pragmatic, nonvalidated phenotyping algorithm. The reported estimates should not be interpreted as national estimates for Mexico overall. Further research is needed to better characterize mixed pain in Mexican clinical populations.