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Validation of the Patient Global Impression scales for use in detrusor overactivity: secondary analysis of the RELAX study
Author(s) -
Tincello DG,
Owen RK,
Slack MC,
Abrams KR
Publication year - 2013
Publication title -
bjog: an international journal of obstetrics and gynaecology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.157
H-Index - 164
eISSN - 1471-0528
pISSN - 1470-0328
DOI - 10.1111/1471-0528.12069
Subject(s) - medicine , placebo , quality of life (healthcare) , population , clinical trial , analysis of variance , physical therapy , urinary incontinence , surgery , alternative medicine , nursing , pathology , environmental health
Objective To assess construct validity of the Patient Global Impression scales (Severity [ PGI ‐S], Bother [ PGI ‐B] and Improvement [ PGI ‐I]) for symptoms of detrusor overactivity ( DO ). Design Secondary analysis of a randomised trial of onabotulinum toxin A. Setting Eight UK urogynaecology departments. Population A total of 240 women with DO refractory to medical treatment randomised to receive 200 iu onabotulinum toxin A or placebo in the RELAX trial and followed up for 6 months. Main outcome measures Urinary diaries and disease‐specific quality of life (QoL) questionnaires were completed at baseline and during follow up. Discriminatory ability of the PGI ‐S, PGI ‐B and PGI ‐I scales to identify symptom severity and change in severity was assessed by comparing mean diary and QoL outcomes across the response categories, analysed by one‐way analysis of variance. Results Data were available from 237 women (98.8%) for validation of PGI ‐S and PGI ‐B at baseline, and 192 women (80%) at 6 weeks follow up for validation of PGI ‐I. Leakage episodes ( P = 0.01), urgency episodes ( P = 0.019), urgency severity ( P = 0.012), and QoL scores (all P < 0.001) were greater in women with more severe problems on PGI ‐S. Similar results were seen for PGI ‐B: leakage ( P = 0.051), urgency episodes ( P < 0.001), urgency severity ( P < 0.001), and QoL scores (all P < 0.001). PGI ‐I responses demonstrated significant relationships with size of change of all variables ( P < 0.001). The generic instrument EQ ‐5D had weaker relationships ( PGI ‐S, P = 0.09; PGI ‐B, P = 0.004; PGI ‐I, P = 0.06), suggesting that it was less sensitive. Conclusions The PGI scales are robust and valid instruments to assess disease severity, bother and improvement after treatment in women with detrusor overactivity.