PEJ Ummels1,2,3, M Barendrecht2, R Mandemakers2
1Zuyd University, Academy of Physiotherapy, Heerlen, Netherlands, 2Avans plus, Physiotherapy, Breda, Netherlands, 3ParaMedisch Centrum Zuid, Physiotherapy, Sittard, Netherlands
Background: The Modified Dutch Anterior Knee Pain Scale (GNAKPS10-16) has been developed to objectify the symptoms presented by young patients (aged 10 - 16 years) with patellofemoral pain syndrome (PFPS) or Osgood-Schlatter’s disease (OSD).
Purpose: This study aimed to investigate the test-retest reliability and responsiveness of the GNAKPS10-16.
Methods: The GNAKPS10-16 was administered three times in 30 patients with OSD and 45 patients with PFPS at baseline (T0), after 2 weeks (T1) and 6 weeks (T2). The degree of change between the measurements was determined by means of the 7-point Global Perceived Effect (GPE) score. Based on the data of unchanged patients (GPE score 3/4/5 at T1), the test-retest reliability was calculated by means of the Intraclass Correlation Coefficient (ICCagreement) with a 95-percent confidence interval (95% CI). In addition, the Standard Error of Measurement (SEM), Smallest Detectable Change (SDC) and Limits of Agreement (LoA) were calculated. The responsiveness was determined based on the GPE score at T2 (3/4/5 unchanged, 1/2 improved) using a receiver-operating characteristic (ROC) curve and expressed in area under the curve (AUC).
Results: The ICCagreement (95% CI)between T0 and T1 was 0.969 (0.927-0.986) for OSD and 0.884 (0.773-0.942) for PFPS. The mean difference between the measurements at T0 and T1 was 0.43 with a standard deviation (SD) of ± 4.17 for OSD and 2.15 (SD ± 6.31) for PFPS. The LoA calculated by means of a Bland and Altman graph were -7.7 and 8.65 for OSD and -10.2 and 14.5 for PFPS. The SEM for OSD was 2.95 with an SDC of ± 8.17; the SEM for PFPS was 4.46 with an SDC of ±12.37. The AUC amounted to 0.971 (0.92-1) for OSD and 0.832 for PFPS (0.7-0.96).
Conclusion(s): In this study, the GNAKPS10-16 revealed a good test-retest reliability for OSD and PFPS, comparable to that of the Dutch AKPS questionnaire. Furthermore, the GNAKPS10-16 showed a good responsiveness in this study.
Implications: The implication for clinical practice is that the questionnaire is manageable; the sum score of the (GNAKPS10-16) is easy to calculate, and subjects need about 5minutes to complete the 12 questions.
Funding, acknowledgements: There was no funding or conflict of interest
Keywords: GNAKPS 10-16, Patellofemoral pain syndrome (PFPS), test-retest reliability and responsiveness
Topic: Research methodology, knowledge translation & implementation science
Did this work require ethics approval? Yes
Institution: Zuyderland- Zuyd
Committee: Jacqueline Jennekens
Ethics number: METCZ20180068
All authors, affiliations and abstracts have been published as submitted.
