Age-Dependent Safety and Effectiveness of Pridinol Versus NSAIDs in Acute (Low) Back Pain: A Secondary Analysis of the Providence Real-World Study

Background: Nonsteroidal anti-inflammatory drugs (NSAIDs) are widely recommended for the treatment of acute (low) back pain, despite modest effectiveness and well-known safety concerns, particularly in older patients. Pridinol is a centrally acting antispasmodic with a mechanism-oriented approach targeting muscle spasm, a key component of acute back pain. While a previous real-world analysis demonstrated a significantly better tolerability and effectiveness of pridinol compared with NSAIDs, age-dependent effects have not yet been systematically evaluated. Objective: To assess the age dependency of effectiveness, safety, and tolerability of pridinol versus NSAIDs in patients with acute (low) back pain under real-world conditions, based on already available data. Methods: This secondary analysis used propensity score-matched real-world data from the German Pain e-Registry (PROVIDENCE study; EUPAS identifier: 49718). A total of 934 patients with acute (low) back pain treated for four weeks with either pridinol (n = 467) or NSAIDs (n = 467) were stratified by age (<65 vs. ≥65 years). Outcomes included the incidence of adverse drug reactions (ADRs), ADR-related treatment discontinuations, time to ADR occurrence, and clinically meaningful improvement in pain-related disability (≥50% reduction in modified Pain Disability Index). Analyses were performed within and between age strata. Results: Overall, ADRs were reported by 9.0% of pridinol-treated patients and 20.8% of NSAID-treated patients (p < 0.001). In the pridinol cohort, ADR rates were virtually identical in patients <65 and ≥65 years (8.9% vs. 9.2%; p = 0.940). In contrast, NSAID-treated patients showed a pronounced age-related increase in ADR incidence (17.3% vs. 32.1%; p < 0.001). ADR-related treatment discontinuation rates under NSAIDs increased markedly with age (5.9% vs. 21.1%; p < 0.001), whereas rates under pridinol remained low and age independent (3.1% vs. 4.6%; p = 0.447). Gastrointestinal and cardiovascular ADRs were the main contributors to the age-related risk increase under NSAIDs, while corresponding events under pridinol were rare across age groups. Clinically meaningful improvement in pain-related disability was achieved with pridinol/NSAIDs in 91.9/48.0% (<65 years) and 88.1/47.7% (≥65 years; p < 0.001 for both). Conclusions: Age is a major modifier of NSAID-related risk but not of pridinol tolerability in acute (low) back pain. While NSAID-associated ADRs and treatment discontinuations increase substantially in patients aged 65 years or older, pridinol demonstrates a stable, age-independent safety profile combined with significantly better functional outcomes. These findings suggest that, particularly in older patients, mechanism-oriented alternatives such as pridinol may offer a more favorable benefit–risk profile than NSAIDs.