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The (ab)use of symptom scores in asthma clinical trials: a systematic review

The (ab)use of symptom scores in asthma clinical trials: a systematic review Geoff Frampton & Jonathan Shepherd. Southampton Health Technology Assessments Centre. Symptoms are important to patients. The multidimensional character of asthma is best captured using multiple outcomes.

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The (ab)use of symptom scores in asthma clinical trials: a systematic review

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  1. The (ab)use of symptom scores in asthma clinical trials: a systematic review Geoff Frampton & Jonathan Shepherd Southampton Health Technology Assessments Centre

  2. Symptoms are important to patients The multidimensional character of asthma is best captured using multiple outcomes Goal of therapy is asthma control Background Symptom scores in asthma clinical research Southampton Health Technology Assessments Centre

  3. Included: Any numeric symptom scales Excluded: 0 1 2 3 - binary (yes/no) scales - symptoms combined with other variables - summary proportions (e.g. % symptom-free days) Scope of this presentation

  4. Reliability (internal consistency, reproducibility) Validity Responsiveness Interpretability Background Ideal features of patient-reported outcomes Southampton Health Technology Assessments Centre

  5. What types of symptom score scales are used in asthma clinical trials ? Do they fulfil the requirements of patient-reported outcomes ? How are the scores interpreted clinically ? Do they reflect circadian variation in asthma ? How are they analysed ? Objective To determine by systematic review: Southampton Health Technology Assessments Centre

  6. www.hta.ac.uk Source of evidence: Systematic reviews of asthma drug effectiveness and safety (SHTAC and PenTAG) National Institute for Health and Clinical Excellence (NICE) review and update of guidelines on inhaled corticosteroids and long-acting beta agonists for management of asthma in adults and children Systematic extraction of symptoms data Methods Southampton Health Technology Assessments Centre

  7. Total number of RCTs RCTs that measured symptom scores 78 RCTs (90%) 14 12 RCTs that used tested scales 10 8 6 4 J:\SHTAC\Projects\Research\Healthcare Associated Infections\Catheter education in critical care\Correspondence with experts 2 0 1981 1986 1991 1996 2001 2006 Results 87 randomized controlled trials (RCTs) published in 32 English language journals, 1985 to 2006 Southampton Health Technology Assessments Centre

  8. Principal symptom domains in 78 asthma RCTs Overall asthma severity 32% Not reported 15% Asthma duration or frequency 13% Dyspnoea 21 different symptom domains 9% Wheeze 9% Cough 8% Multiple domains 7% Other 7% Results – symptom assessments Southampton Health Technology Assessments Centre

  9. Numerical symptom scales used in 78 asthma RCTs 4-item 46% 6-item 19% 5-item 12% Type of scale 10 unique numeric scales 7-item 10% Scale not reported 6% > 7 items 5% Other 3% Results – symptom assessments Southampton Health Technology Assessments Centre

  10. Timing of symptom assessments in 78 asthma RCTs Day 32% 28% Night Unclear 8% Not reported 8% 8 different timings of symptom assessments Sum of (day + night) 7% am 7% pm 6% other 5% Results – symptom assessments Southampton Health Technology Assessments Centre

  11. Asthma severity scores Day Night 1 2 3 4 5 6 7 8 9 10 11 11 randomized controlled trials Results – circadian patterns Symptom score 2 1 0 -6 Southampton Health Technology Assessments Centre 134

  12. Statistically significant effects of inhaler treatment on scores Method of analysis of symptom scores 37% 76% Not reported Number of RCTs 1986 1991 1996 2001 2006 Results – analysis methods Southampton Health Technology Assessments Centre 134

  13. Asthma symptom scales appear to be almost all unique There is hardly any information on their reliability, validity and responsiveness How should we interpret the numeric scores clinically ? (e.g. minimal important difference; NNT) What do the robust diurnal patterns in symptom scores mean ? Which are the correct statistical analyses? Discussion Southampton Health Technology Assessments Centre

  14. Thank you for your attention! The views and opinions expressed in this presentation are those of the authors and do not necessarily reflect those of the UK Department of Health In conclusion, asthma clinical trials should… 1. Share the use of fewer, tested, symptom score instruments 2. Provide guidance on clinical interpretation 3. Precisely report the timing of symptom assessments 4. Explain the statistical testing rationale and any assumptions Southampton Health Technology Assessments Centre

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