Objective
Interpretation of the Achilles tendon Rupture Score (ATRS) is challenging because no knowledge exists about at which score the patients consider the outcome of treatment as satisfactory. The aims of this study were 1) to describe the proportion of patients who find their symptom levels to be satisfactory, to reflect treatment failure or neither, and 2) to estimate the Patient Acceptable Symptom State (PASS) and the Treatment Failure (TF) threshold values for ATRS at 6 months, 1 year, and 2 years after ATR.
Methods
The nationwide Danish Achilles tendon Database (DADB) includes patients treated operatively or non-operatively after ATR. 1 May 2020 the included patients were asked at 6 months, 1 year, or 2 years after their ATR whether they considered their symptom level to be satisfactory (PASS anchor question), and if not, if they considered their symptom level to reflect treatment failure (TF anchor question). Patients who on 1 January 2021 had answered both the anchor questions and the ATRS were included in the study population for the given time point. The PASS and TF threshold values of ATRS at each follow-up time point were estimated using the adjusted predictive modeling method, which is based on logistic regression. Confidence Intervals (CI) were derived with non-parametric bootstrapping.
Results
166 (51%) patients were included at 6 months, 248 (50%) patients at 1 year, and 287 (57%) patients at 2 years. The proportion of patients who considered their symptom level to be satisfactory was 61% at 6 months, 50% at 1 year, and 66% at 2 years. The proportion of patients who considered their symptom level to reflect treatment failure was 5% at 6 months, 11% at 1 year, and 10% at 2 years. The ATRS PASS threshold value (95% CI) was 49 (46-52) at 6 months, 57 (54-60) at 1 year, and 52 (49-55) at 2 years. TF threshold value (95% CI) was 30 (23-36) at 6 months, 33 (26-40) at 1 year and 35 (29-39) at 2 years.
Conclusion
The PASS threshold value for ATRS ranged between 49 and 57. The TF threshold values ranged between 30 and 35. The values can help interpret the outcome of ATR when measured with the ATRS. At 6 months to 2 years after ATR, 50-66% of the patients had a satisfactory symptom level, while 5-11% considered their symptom levels to reflect treatment failure.