Table 1 Study objectives

Primary

To determine whether use of the PReDicT Test to direct antidepressant treatment results in an increased proportion of depressed patients showing a response (defined as 50% or greater reduction from baseline Quick Inventory of Depressive Symptoms – Self-Rated-16 (QIDS) score) to treatment at week 8 compared to TaU.

Secondary efficacy objective

To compare the change from baseline in QIDS scores (i.e. treated as a continuous variable) at week 8 between depressed patients receiving treatment directed by the PReDicT Test and those receiving TaU

To determine whether use of the PReDicT Test to direct antidepressant treatment results in an increased proportion of depressed patients showing a response to treatment at week 8 compared to TaU, where response is defined as a decrease of 50% or more from baseline Montgomery-Åsberg Depression Rating Scale (MADRS) scores [10].

To determine whether use of the PReDicT Test to direct antidepressant treatment results in an increased proportion of depressed patients achieving remission at week 8 compared to TaU where remission is defined as a QIDS score of 5 or less.

To determine whether use of the PReDicT Test to direct antidepressant treatment results in an increased proportion of depressed patients achieving remission at week 8 compared to TaU where remission is defined as a MADRS score of 7 or less.

To compare the change from baseline in QIDS score (i.e. treated as a continuous variable) at week 12 between depressed patients receiving treatment directed by the PReDicT Test and those receiving TaU.

To compare the change from baseline in Quick Inventory of Depressive Symptoms – Self-Rated-16 (QIDS-SR-16) score (i.e. treated as a continuous variable) at 24 and 48 weeks between depressed patients receiving treatment directed by the PReDicT Test and those receiving TaU

Health economic objectives

To determine the impact on societal costs and cost-effectiveness/cost-utility of the PReDicT Test intervention in comparison to TaU over 24 weeks and over 48 weeks if feasible

Acceptability and implementation objectives

To explore how the PReDicT Tests are used by various stakeholders (patients, prescribing physicians and support staff), and the impact this has on care and care processes, in order to refine its future implementation across different countries.

Exploratory objectives

To compare the change from baseline in Generalised Anxiety Disorder Questionnaire, 7-item version (GAD-7) [11] score (i.e. treated as a continuous variable) at week 8 between depressed patients receiving treatment directed by the PReDicT Test and those receiving TaU.

To compare the change from baseline on the depression and anxiety items (analysed separately) of the QIDS at week 8 between depressed patients receiving treatment directed by the PReDicT Test and those receiving TaU.

To determine the change of cognitive function (assessed using the Digit Symbol Substitution Test (DSST) [12] ) from baseline to week 8 between depressed patients receiving treatment directed by the PReDicT Test and those receiving TaU.

To compare the change from baseline in self-reported social and occupational functioning at weeks 8, 24 and 48 between depressed patients receiving treatment directed by the PReDicT Test and those receiving TaU.

Safety objective

To obtain evidence, as required by medical devices legislation, that the PReDicT Test is safe for use in primary care.