Warner 2006.
| Methods | RCT (parallel design) Study duration: 2 months Setting: six asthma/allergy clinics, Detroit, Michigan, USA |
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| Participants | 180 eligible, 61 randomly assigned, 50 completed the study Intervention (writing on trauma or problem ever experienced): 28 Control (writing on time management): 22 Age: mean 14 years Sex: male 21, female 29 Physician‐diagnosed asthma Severity: 40% had mild persistent asthma, 52% had moderate persistent and 8% had severe persistent Inclusion criteria: adolescent participants, aged 12 to 17, with at least mild persistent asthma Exclusion criteria: having only seasonal or exercise‐induced asthma, the presence of a serious medical condition other than asthma and current use of psychotropic medication or participation in counselling or psychotherapy and known to have cognitive impairment |
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| Interventions | Intervention: write about a trauma or problem ever experienced. Participants encouraged to write about the same event for 15 to 20 minutes daily for three consecutive days Control: write about time management. Written exercise varied across three days; activity over the past week (day 1), activity over the past 24 hours (day 2) and plan for next 24 hours (day 3) Both groups wrote in a private place at home or elsewhere |
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| Outcomes | FEV1 % predicted measured by spirometry in accordance with ATS guidelines, asthma symptoms (9‐item Asthma Sum Scale), positive affect and negative affect (30‐item Positive and Negative Affect Schedule for Children), internalisation of behaviour problems (Youth Self Report), functional disability (15‐item Functional Disability Inventory) Outcome measured at baseline and at 1 and 2 months post intervention |
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| Notes | No sample size calculation reported Spirometry data available for 32 participants only Two groups similar in terms of demographics and asthma history variables at baseline Study funded by dissertation grants from the Blue Cross/Blue Shield of Michigan Foundation, Wayne State University and the Ashok and Ingrid Sarniak Endowment through Children’s Hospital of Michigan, USA |
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| Risk of bias | ||
| Bias | Authors' judgement | Support for judgement |
| Random sequence generation (selection bias) | Low risk | "A random numbers table was used to randomise participants to groups separately for each gender" |
| Allocation concealment (selection bias) | Low risk | Study author confirmed the use of sealed envelopes for assignment |
| Blinding of participants and personnel (performance bias) All outcomes | Low risk | Study authors contacted to provide more information on blinding; these authors confirmed the blinding of study participants and researcher during recruitment and baseline assignment |
| Blinding of outcome assessment (detection bias) All outcomes | High risk | Information on blinding of outcome assessors not reported in the study |
| Incomplete outcome data (attrition bias) All outcomes | Low risk | Missing data balanced in number across the intervention group and the control group (6 and 5 respectively) |
| Selective reporting (reporting bias) | Low risk | All possible outcomes stated in the methods section reported in the results section |
| Other bias | Unclear risk | Inability to assess lung function for all participants may have introduced a selection bias. Insufficient information on whether smoking was taken into account |
Abbreviations: ATS: American Thoracic Society; COPD: chronic obstructive pulmonary disease; GP: general practitioner; RA: rheumatoid arthritis; RCT: randomised controlled trial; FEV1: forced expiratory volume in one second; FVC: forced vital capacity.