Strengths and limitations
sleep disturbance, fatigue, IUT, worry, depression, irritability
RECRUITMENT
This study had several strengths. Generalizability to other primary health care settings was strengthened by the recruitment of patients and therapists from regular primary health care and by keeping exclusion criteria to a minimum. In addition to measuring symptoms of worry and depression, the study also investigated functional impairment, quality of life, medication use, sick leave, and participants’ perceptions of the treatments and of study participation. Moreover, several therapists were involved in treatment, all sessions were audio-recorded, the therapists were blinded to which session would be assessed, and the therapists’ competence in and adherence to protocol were assessed by independent assessors.The study also had several limitations. First, only one large primary health care center in an urban area participated, which reduces the generalizability of the findings to other primary health care populations. Moreover, despite randomization, the distribution is uneven between the groups regarding married/cohabiting versus living alone, which may have affected the results. Second, therapists’ competence in and adherence to the protocols was assessed in only a small proportion of the sessions as one of several feasibility measures, and inter-rater reliability was not ascertained. Third, due to the lack of an inactive control group, no conclusive causal inferences of the effects of IUT and MCT can be made; however, because of the differential effects it is likely that the treatments were at least partly responsible. Fourth, therapists were not randomized or allocated to perform both IUT and MCT, but rather chose which treatment they wanted to provide. Thus, their prior interest and competence in the treatment they selected could have biased the findings.Finally, no sample size calculation was conducted, as the primary aim of the present study was to investigate feasibility. The mostly large effect sizes nevertheless suggest that the preliminary results regarding treatment effects are reliable. However, the lack of a sample size calculation constitutes a major limitation that may affect generalizability of the results.To obtain a fuller picture of how treatment may improve the complex symptoms of GAD, in addition to assessing worry, future studies could investigate the severity of other common symptoms in patients with GAD, such as fatigue, sleep disturbance, irritability, and muscle tension. Because patients with GAD visit primary health care frequently for a variety of symptoms, future studies should also consider use of care as an outcome. Furthermore, future studies should consider using clinician-assessed measures rather than relying solely on self-report.Even though pharmaceutical treatment was supposed to remain stable during the treatment period, some participants reduced or stopped medication, and others started medication, which could have affected the results. This finding underscores the need to monitor medication use during an RCT.