Net Promoter Score: a prospective, single-centre observational study assessing if a single question determined treatment success after primary or revision hip arthroplasty.

BACKGROUND: Our study aimed to identify the relationship between treatment outcome assessed by patient-reported outcomes (PROMs) and satisfaction measured by calculation of the Net Promoter Score (NPS), which identifies promoters, following total hip arthroplasty (THA). The aim was to evaluate this association separately in primary and revision THA and to determine thresholds based on PROMs that identify detractors of the surgical procedure or the centre.

METHODS: A total of 1,243 patients who underwent primary or revision THA at our hospital were asked to complete questionnaires of the Oxford Hip Score (OHS), Euroquol-5D (EQ-5D) and information on pain intensity preoperatively, three and 12 months after surgery. Postoperatively, the patients were additionally asked about their satisfaction with the procedure and the hospital by using three different NPS questions. The association between PROMs and NPS was evaluated based on group comparisons of primary or revision THA and receiver operating characteristics analysis (ROC) to determine threshold values.

RESULTS: At 12 months the NPS of all three questions were invariably linked to treatment outcome in patients after primary THA and patients with a single revision. In these two treatment groups, promoters always showed significantly better PROM scores than detractors. The NPS score was always higher in the primary group in comparison to the single revision group, e.g. 66.4% would undergo the procedure again in the first group, while only 33.0% would opt for this in the latter group. The high thresholds for the PROMs at 12 months, that were calculated by ROC analysis to identify promoter/detractors, indicate that patients` satisfaction required very good joint function and pain relief. However, the NPS was not a suitable tool to identify patients who need further care in an early phase after surgery.

CONCLUSIONS: With NPS already a single question or a single parameter provides the desired information regarding patient satisfaction and also treatment success.

TRIAL REGISTRATION: The study was approved by the Ethics Committee at the Medical Faculty of the University Rostock: "Ethikkommission an der Medizinischen Fakultät der Universität Rostock", Address: St.-Georg Str. 108 18055 Rostock, Germany, reference number: A2015-0055.