Smyth 1999.
| Methods | RCT (unbalanced design; 2 of every 3 participants allocated to the experimental condition) Study duration: 4 months Setting: outpatient community residents drawn from private and institutional practice, North Dakota, USA |
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| Participants | 70 eligible, 70 randomly assigned, 61 received the intervention and 58 completed the study Intervention (writing on most stressful experience): 39 Control (writing about plan for the day): 19 Age: mean age 41 (SD ± 17.4) years, range not reported Sex: male 15, female 43 Physician‐diagnosed asthma based on history Inclusion criteria: patients with physician‐diagnosed asthma required to provide a documented reduction in expiratory function (in physician records or when evaluated by study staff) Exclusion criteria: ongoing psychotherapy or having a defined psychiatric disorder, using a medication that could interfere with symptom report, being deemed unable to comply with the protocol, being unable to write for a duration of 20 minutes |
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| Interventions | Intervention: write on most stressful experience ever undergone Control: write about plans for the day Participants in both groups wrote for 20 minutes on 3 consecutive days a week. They could write about the same topic for three sessions or move from one topic to another. Writing took place in private rooms located in study laboratory |
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| Outcomes | FEV1 % predicted measured by spirometry in accordance with ATS guidelines Outcomes measured at baseline and at 2 weeks, 2 months and 4 months post intervention |
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| Notes | Trial included asthma and RA participants. Only the data on participants with asthma were extracted and included in the review Sample size calculation done No other data reported except FEV1 % predicted On email correspondence, study author informed that other outcomes were measured, but data analysis was carried out for FEV1 % predicted only Control and experimental groups similar at baseline in terms of demographic measures, health behaviours including smoking or psychological measures and asthma outcome Study funded by the Fetzer Institute, Kalamazoo, Michigan, USA |
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| Risk of bias | ||
| Bias | Authors' judgement | Support for judgement |
| Random sequence generation (selection bias) | Low risk | "Participants were randomised into the control or experimental group using a computer‐generated random assignment scheme" |
| Allocation concealment (selection bias) | Low risk | "Assignments were kept in sealed opaque envelopes until participants were scheduled to complete the writing intervention" |
| Blinding of participants and personnel (performance bias) All outcomes | Low risk | "Neither patients nor physicians were informed of the assignment" |
| Blinding of outcome assessment (detection bias) All outcomes | High risk | "Statistical analyses were conducted primarily by the first author, who was aware of group assignment" |
| Incomplete outcome data (attrition bias) All outcomes | Low risk | Nine participants dropped out of the study before receiving the intervention; however, only two of 22 participants in the intervention arm left the study after randomisation |
| Selective reporting (reporting bias) | High risk | Only FEV1 reported as a study outcome, no other study outcomes reported |
| Other bias | Unclear risk | Insufficient information |