Can P1NP Levels Influence Management Planning for Patients With a Fragility Hip Fracture Receiving Anti-resorptive Medications?

backgroundThe procollagen type 1 N-terminal propeptide (P1NP), a byproduct of type I collagen synthesis, is useful in clinically monitoring anti-resorption medications. The role of P1NP in anti-resorption therapy in older bisphosphonate-taking individuals who have suffered another fracture is unclear.

objectivesThis study aims to describe serum P1NP levels in patients aged ≥60 years who sustained a fragility neck of femur fracture while receiving osteoporosis therapy and to describe how P1NP results were associated with subsequent bone health management decisions, defined as documented decisions to continue, stop, or change osteoporosis therapy (including switch/escalation) and/or request additional investigations.

methodsThis retrospective descriptive cohort study, conducted between March 2017 and September 2021, involved patients aged 60 years or older who experienced intra- or extracapsular femoral neck fractures while receiving osteoporosis therapy and had serum P1NP assessed before surgery. Routinely collected data were extracted from departmental databases and systems accessible through the NHS computers at East Surrey Hospital as part of an ongoing quality improvement project.

resultsOut of the 2,303 total fractures during the study period, 58 patients (2.5%) had serum P1NP levels tested. The mean age was 84.6 ± 8.08 years, with a female-to-male ratio of 8.7:1; 34 (58.6%) had intracapsular and 24 (41.6%) had extracapsular types of fractures. Eighteen patients (31%) had P1NP levels of 40 ug/l or higher; six (10.3%) had P1NP levels between 36 and 39 ug/l, and 34 patients (58.6%) exhibited suppressed P1NP levels (below 35 ug/l). For those who had suppressed P1NP, five (55.6%) of the nine patients (who had been receiving treatment for over five years) had their treatment discontinued, two (22.2%) had their treatment plans modified because of DXA scan results, and two remained on the same treatment plan. Three patients on therapy for up to five years had P1NP levels above 40 ug/l owing to memory loss or inexperience with oral alendronate; therefore, adherence was low. Change to IV zoledronate or patient education was offered.

conclusionIn this selected cohort, measuring pre-operative P1NP levels supported patient-centred multidisciplinary (MDT) bone health planning. Clinicians considered P1NP alongside DXA findings and the broader clinical context when documenting MDT post-fracture bone health plans, with management changes commonly recorded among patients receiving long-term therapy (>5 years). Notably, in this long-term treated group, suppressed P1NP commonly coincided with documented decisions to stop or adjust therapy. Given the retrospective design, small sample size, lack of a comparator group, and absence of outcome data, these findings provide real-world insight into current practice and may support development of a more standardised approach to incorporating P1NP into post-fracture bone health pathways.