Quality of life changes in cluster headache: Convergent validity, responsiveness, and interpretability of the Cluster Headache Quality of Life scale as a patient‐reported outcome measure

OBJECTIVE: Cluster headache (CH) significantly impacts patients' quality of life (QoL). We aim to validate the Cluster Headache Quality of Life scale (CHQ) for measuring QoL changes in patients with CH. METHODS: In this multicenter, prospective, longitudinal psychometric validation study, participants, all with chronic CH (CCH), completed the CHQ at a 3-monthly interval alongside headache diaries and general QoL questionnaires (36-item Short Form [SF-36], Hospital Anxiety and Depression Scale [HADS], and EuroQol 5 Dimensions [EQ-5D]). CHQ's ability to measure changes was validated in three steps following COSMIN guidelines: (1) convergent validity, (2) responsiveness, and (3) interpretability. Baseline scores were used for step 1; change scores for steps 2 and 3 (Δ baseline-follow-up). Twelve correlation hypotheses were formulated and tested for steps 1 and 2. Validity was rated by % rejected hypotheses (high: ≤25%, moderate: 26%-50%, poor: ≥50%). Data were collected in the Netherlands (Leiden, Nijmegen, Heerlen) between 9 December 2021 and 18 November 2024. RESULTS: For step 1, 117 participants were included (n = 70 for SF-36/HADS analyses, n = 42 for EQ-5D analyses) and 82 were included for steps 2 and 3 (n = 48 for SF-36/HADS analyses, n = 29 for EQ-5D analyses). At baseline, overall QoL was poor (CHQ: 60.9 ± 23.1, SF-36: 46.7 ± 19.9) and worse in participants with more intense and frequent CH attacks (>CHQ scores: β = 2.92 (95% confidence interval [CI] 0.91 to 4.93), p = 0.005; β = 0.27 (95% CI 0.02 to 0.53), p = 0.033). Convergent and responsiveness validity was high (≤25% hypotheses rejected). CHQ baseline scores correlated strongly with the HADS, SF-36, and EQ-5D (ρ = 0.68, ρ = -0.60, ρ = -0.52), but weakly with attack frequency (ρ = 0.27). Change scores correlated strongly with HADS and SF-36 (ρ = 0.51, ρ = -0.56) and moderately with EQ-5D (ρ = -0.38). Step 3 indicated ≤ -3.5 points change as clinically relevant improvement and ≥7.5 points as deterioration. CONCLUSION: The CHQ has a high validity to measure change in QoL. CH attack frequency influences QoL, but QoL is more strongly correlated with mental health and activity restrictions than attack frequency. Implementing the CHQ may improve understanding of disease burden, enabling more targeted treatment strategies and thus improving overall disease management.