Illustrative example of rating the certainty in evidence in the absence of a single estimate of effect
| GRADE domain | Judgement | Concerns about certainty domains |
|---|---|---|
| Methodological limitations of the studies | One out of five trials7 had low risk of bias in the three items assessed (sequence generation, allocation concealment and blinding) but it was the smallest study (46 participants). Two other trials (56 and 129 participants)3 5 did not report on any of the risk of bias items; making judgements not possible, which was concerning. The remaining two trials4 6 (235 and 157 participants) explicitly reported lack of blinding, unclear sequence generation and allocation concealment. Therefore, we judged the trials to have serious methodological limitations. | Serious |
| Indirectness | The patients, intervention and comparators in the studies all provide direct evidence to the clinical question at hand. All interventions included an educational component (with some variation in the direct respiratory therapy component). The type and severity of the symptoms (outcome) was assessed using different scales in different trials. We judged the evidence to have no serious indirectness but noted some variability in the intervention and outcome measure. | Not serious |
| Imprecision | The total number of patients included in all the trials was ∼600. Some trials reported small reductions, and other trials reported ‘non-significant results’ likely because of enrolling a small number of participants which resulted in wide CIs that included meaningful benefits and no effects. We judged the evidence to have borderline imprecision. | Not serious, borderline |
| Inconsistency | The direction and magnitude of effect varied across the different trials. Overall the results showed either small reduction in symptoms or no change. Two trials,3 4 showed a small effect on dyspnoea at the 5% level using the Borg scale in favour of self-management education programme. In the third trial,5 they found no significant between-group differences in the proportion of days rated as mild, moderate or severe in their respiratory status in symptom diaries. In the fourth trial,6 no significant between-group differences were seen in mean breathlessness and sputum production scores over 2-week periods. However, small statistically significant differences in mean cough and sputum colour scores were seen in favour of the intervention group. In the fifth trial,7 no significant differences were found between the scores of the intervention and control group during exacerbations (breathlessness, sputum volume and sputum colour). We judged the evidence to have serious inconsistency. | Serious |
| Publication bias | We did not strongly suspect publication bias because both negative and positive trials were published, and the search for studies was comprehensive. | Not suspected |
The outcome of interest is respiratory symptoms. Data are derived from a systematic review of self-management programmes in patients with chronic obstructive pulmonary disease.