Outcome assessment in frozen shoulder trials: A systematic review and COSMIN-informed recommendations.

In 30 seconds

This systematic review mapped outcome measures in 927 randomized controlled trials (RCTs) of frozen shoulder and conducted a COSMIN-informed appraisal of measurement-property evidence for commonly used instruments. Outcomes most often addressed pain, mobility and shoulder function: range of motion (ROM) appeared in 448 studies (48.3%), and VAS/NRS pain in 327 (35.3%). The most frequent pairing was ROM plus VAS/NRS pain (198 studies, 21.4%). The authors found measurement evidence for six instruments or measure families, with comparatively more complete frozen shoulder-specific evidence for SPADI among commonly used shoulder-specific patient-reported measures.

Key findings

• ROM was reported in 448 studies (48.3%), VAS/NRS pain in 327 (35.3%), and global improvement or total effective rate in 260 (28.0%).
• ROM plus VAS/NRS pain was the most common outcome pairing, used in 198 studies (21.4%).
• The appraisal synthesized 10 supporting evidence entries covering six instruments or measure families; SPADI had comparatively more complete frozen shoulder-specific evidence among commonly used shoulder-specific PROMs.
• Evidence remains limited for SPADI content validity, responsiveness, interpretability, and minimal important change.

Why it matters

Heterogeneous outcome selection makes results across frozen shoulder trials harder to compare and limits evidence synthesis. The review shows that frequently used measures do not necessarily have equally complete measurement-property evidence. Its provisional recommendations offer a structured way to select complementary outcomes while recognizing that important evidence gaps remain.

What to keep in mind

The COSMIN-informed appraisal was not a full COSMIN systematic review and did not include formal COSMIN-GRADE certainty ratings. Recommendations are provisional, not a formal consensus-based core outcome set.