Responsiveness and interpretability of the Knee Outcome Survey − Activities of Daily Living Scale (KOS-ADLS) in patient with knee pain

Autori

Roberta La Marca [Department of Medicine and Health Science “Vincenzo Tiberio”, University of Molise, Campobasso, Italy]

Emanuele Tortoli [Department of Medicine and Health Science “Vincenzo Tiberio”, University of Molise, Campobasso, Italy]

Alessandro Ugolini [Independent researcher, Empoli (FI), Italy]

Leonardo Pellicciari [IRCCS Istituto delle Scienze Neurologiche di Bologna, Bologna, Italy]

Background and aims

Knee pain accounts for about one-third of musculoskeletal complaints in primary care, significantly

impacting function and quality of life. Effective treatment evaluation requires instruments

responsive to meaningful changes over time. The Knee Outcome Survey-Activities of Daily Living

Scale (KOS-ADLS) is a reliable, knee-specific patient-reported outcome measure used globally to

assess physical function in daily activities. However, limited studies have examined its

responsiveness and interpretability by means of the minimal important change (MIC) according to

COSMIN guidelines. This study evaluates the responsiveness and MIC in patients with various knee

disorders, including surgical and non-surgical cases, from both patient and clinician perspectives,

following COSMIN recommendation.

Methods

115 (60 non-surgical, 55 surgical) adult patients with knee injuries, recruited from three

physiotherapy clinics, were included in this clinimetric study. KOS-ADLS and other specific and

generic measures were administered to each patient at baseline and after physiotherapy treatment.

After the treatment, a 15-point global rating of change (GROC) scale were administered to patients

and physiotherapy to assess the perceived improvement by patients’ and physiotherapists’

pespective. Responsiveness was assessed by formulating 12 a-priori hypotheses, and MIC was

calculated by dividing the samples into “clinically improved” and “not clinically improved”

according to the GROC results. All analyses were performed separately for the total, surgery and

no-surgery samples.

Results

The KOS-ADLS demonstrated satisfactory responsiveness (11 out of 12 hypotheses were met),

with large effect size (ES=0.90) and standardized response mean (SRM=1.03) values in the total

sample, with higher values in the surgical group (ES=1.25, SRM=1.40) compared to the non-

surgical group (ES=0.76, SRM=0.81). The AUC was higher than 0.70 across samples and patients’

and physiotherapists’ perspectives. The MIC ranged from 8.5 to 18 points, varying between the

sample and patients’ and physiotherapists’ perspectives, with the highest values in surgical patients

and from the physiotherapist’s perspective.

Conclusion

This study demonstrated satisfactory responsiveness of the KOS-ADLS according to COSMIN

standards in patients with a wide range of knee pathologies, especially in surgical patients. Both

patient and physiotherapist assessments showed higher responsiveness in clinically improved

individuals, with MIC values ranging from 8.5 to 18 points, generally higher in surgical sample and

from the physiotherapist’s perspective. Physiotherapists reported slightly greater changes than

patients, reflecting differences in recovery perception. MIC discrepancies between patients and

clinicians highlight the need for clear communication during rehabilitation. Study limitations

include short follow-up and limited generalizability beyond Italian clinical settings.

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