Do Latino Populations Have a Distinct Pain Sensitivity? A Quantitative Sensory Testing Study in Chilean Healthy Volunteers

BACKGROUND: Quantitative sensory testing (QST) interprets somatosensory function against normative data, most commonly from the German Research Network on Neuropathic Pain (DFNS), based on European volunteers. Whether these reference values describe admixed Latin American populations is unknown. METHODS: We retrospectively analysed DFNS QST profiles (dorsum of the foot) in 144 healthy Chilean volunteers. We tested sex differences, identified somatosensory phenotypes using unsupervised clustering, examined rating-scale effects on mechanical pain sensitivity (MPS) in an independent group (n = 21; 0-100 vs. 0-10 scale), and established preliminary Chilean QST reference values overall and stratified by age (< 40 vs. ≥ 40 years). RESULTS: Detection thresholds were largely normal. The prominent finding was in MPS (mean z = 1.75 ± 1.13), with gain-of-function in 48% of volunteers; no other parameter was comparably deviated. This effect was sex-independent and survived multiple-comparison correction (Cohen's d = 1.54). Replacing the pain-rating scale from 0-100 to 0-10 did not reduce MPS ratings, which were higher with the 0-10 scale under some conditions. The gain-of-function occurred in both age strata (50.0% and 44.6%), and MPS remained unchanged with age. CONCLUSIONS: Healthy Chilean volunteers show markedly increased MPS relative to DFNS data. This phenotype was not explained by the rating scale used and disappeared when assessed against local reference values. These findings suggest population-specific differences in mechanical pain processing or reporting, including possible biological contributions such as Native American ancestry and Neanderthal-introgressed SCN9A variants, and question the use of imported normative data in Latin American subjects. SIGNIFICANCE STATEMENT: Nearly half of healthy Chilean volunteers were classified as mechanically hypersensitive by European QST reference values, but the discrepancy was confined to MPS, the most subjective parameter of the DFNS protocol, which disappeared when local reference values were applied.