Changes and thresholds in the Forgotten Joint Score after total hip arthroplasty

Abstract

Aims The aim of this study was to identify the minimal clinically important difference (MCID), minimal important change (MIC), minimal detectable change (MDC), and patient-acceptable symptom state (PASS) in the Forgotten Joint Score (FJS) according to patient satisfaction six months following total hip arthroplasty (THA) in a UK population. Methods During a one-year period, 461 patients underwent a primary THA and completed preoperative and six-month FJS, with a mean age of 67.2 years (22 to 93). At six months, patient satisfaction was recorded as very satisfied, satisfied, neutral, dissatisfied, or very dissatisfied. The difference between patients recording neutral (n = 31) and satisfied (n = 101) was used to define the MCID. MIC for a cohort was defined as the change in the FJS for those patients declaring their outcome as satisfied, whereas receiver operating characteristic curve analysis was used to determine the MIC for an individual and the PASS. Distribution-based methodology was used to calculate the MDC. Results Using satisfaction as the anchor, the MCID for the FJS was 8.1 (95% confidence interval (CI) 3.7 to 15.9; p = 0.040), which was affirmed when adjusting for confounding. The MIC for the FJS for a cohort of patients was 17.7 (95% CI 13.7 to 21.7) and for an individual patient was 18. The MDC90 for the FJS was eight, meaning that 90% of patients scoring more than this will have experienced a real change that is beyond measurement error. The PASS threshold for the FJS was defined as 29. Conclusion The MCID and MIC can be used respectively to assess whether there is a clinical difference between two groups, or whether a cohort or patient has had a meaningful change in their FJS. Both values were greater than measurement error (MDC90), suggesting a real change. The PASS threshold for the postoperative FJS can be used as a marker of achieving patient satisfaction following THA. Cite this article: Bone Joint J 2021;103-B(12):1759–1765.

The Forgotten Joint Score patient-acceptable symptom state following primary total hip arthroplasty

“…Despite these previously conducted studies, consensus on the establishment of a PASS value for the FJS-12 following THA remains inconclusive in the literature. This is evidenced by the findings reported in a recently published study by Robinson et al, 21 which defined the PASS threshold for the FJS-12 to be 29 at six months after THA for the UK population using ROC curve analysis. This discrepancy compared to other similar studies may be due to the recognized difference in postoperative FJS-12 scores between various populations following arthroplasty rendering these estimations to be non-universal.…”

“… 39 Additionally, variation in the anchor question has the potential to produce different results. 40 Unlike our study which used the HOOS, JR as the anchor, Robinson et al 21 used a five-point Likert scale (very satisfied, satisfied, neutral, dissatisfied, or very dissatisfied) to assess patient satisfaction. Furthermore, their results are limited to six months following surgery, while our study evaluates the PASS threshold at one year after THA.…”

“…5,33,34 Nevertheless, the threshold defining a "forgotten joint" remains relatively inconclusive in the literature. [19][20][21]35,36 Using data collected from 780 patients, we derived the PASS values of 66.68 and 92.20 for the FJS-12 at one-year follow-up after primary THA using the ROC and 75th percentile approaches, respectively. Previous studies have reported that factors other than surgery, such as early postoperative movement, may influence PROMs and factors such as room conditions or inefficient communication with the nursing staff could decrease the overall satisfaction of the patients after THA.…”

“… 5 , 33 , 34 Nevertheless, the threshold defining a “forgotten joint” remains relatively inconclusive in the literature. 19 - 21 , 35 , 36 Using data collected from 780 patients, we derived the PASS values of 66.68 and 92.20 for the FJS-12 at one-year follow-up after primary THA using the ROC and 75th percentile approaches, respectively.…”

“…Despite previous studies having demonstrated the validity and reliability of the FJS-12, the PASS value for this questionnaire remains relatively unexplored in the literature. [18][19][20][21] This study aims to define the PASS value for the FJS-12 at one year following primary THA using the Hip disability and Osteoarthritis Outcome Score, Joint Replacement (HOOS, JR) as an anchor.…”