Cost-benefit Evaluation of a Transdiagnostic Psychological Treatment for Emotional Disorders in Primary Care (PsicAP-Costs)

The PHQ-9 (Kroenke et al., 2001) is the depression module of the PHQ (Díez-Quevedo et al., 2001; Spitzer et al., 1999), that scores the 9 DSM-IV depression criteria present in the last two weeks from 0 ("not at all") to 3 ("nearly every day"). A score of 10 is usually set as the cut-off point for major depression disorder (MDD): a score of 10-14 indicates minor depression, moderate MDD, or dysthymia; 15-19, moderately severe MDD; and 20-27, severe MDD. This tool has been tested in Spanish primary care centres (McDonald's ω = .89) (Muñoz-Navarro, Cano-Vindel, Medrano et al., 2017), finding 12 as the best cut point for MDD diagnosis (sensitivity of 84% and specificity of 78%) compared with 10 (sensitivity of 95% and specificity of 67%).

The GAD-7 (Spitzer et al., 2006) assesses common anxiety symptoms in the last two weeks, scoring from 0 ("not at all") to 3 ("nearly every day"). Cut points of 5, 10, and 15 represent mild, moderate, and severe anxiety, respectively. The algorithm sets 8 as the cut point for GAD, however it has been found that a score of 10 is more optimal (Spitzer et al., 2006). We will use the version validated by García-Campayo et al. (2010), that was recently tested in primary care centres (Cronbach's α = .83) (Muñoz-Navarro, Cano-Vindel, Moriana et al., 2017), confirming the score of 10 as the best diagnostic criterion (sensitivity of 87% and specificity of 78%).

The PHQ-PD is the specific panic disorder module of the PHQ and scores each DSM-IV criterion as "yes" or "no" (Wittkampf et al., 2011). Muñoz-Navarro et al. (2016) tested it in Spanish primary care settings and modified the original algorithm to increase the sensitivity for PD diagnosis: the most optimal cut-off point for screening purposes was 5 (the first item [for panic screening] and one of the following three, plus four somatic symptoms) (sensitivity of 77% and specificity of 72%).

The PHQ-15 (Kroenke et al., 2002) is the somatization module of the PHQ. It includes 13 somatic symptoms plus 2 from the PHQ-9 (sleeping problems and fatigue). Scores of 5, 10, and 15 represent low, medium, and high somatic symptom severity, respectively. To screen a somatization disorder, whereas the original algorithm needs of at least a score of 2 in three or more somatic symptoms (sensitivity of 78% and specificity of 71%) (van Ravesteijn et al., 2009), the cut point usually used is 10; nevertheless, since this can be obtained with ten symptoms of mild severity, we decided to join both criteria to screen the disorder. Furthermore, an absence of biological cause is also often required (since PHQ-15 does not distinguish between medically explained and unexplained symptoms) (Kroenke et al., 2002), but the self-administered nature of the PHQ-15 makes difficult to determine this. The PHQ-15 has been validated with Spanish psychiatric outpatients (α = .78) (Ros et al., 2010).

The SDS (Sheehan et al., 1996) is a self-administered test that measures the subjective symptom-related impairment with five 11-point Likert items. The three first items rate key areas in the past month: work, social life/leisure activities, and family life/home responsibilities. It has two additional items to assess stress level and perceived social support in the past week. We will use the Spanish version developed by Bobes et al. (1999), that has shown good properties with primary care population (α = .83) (Luciano et al., 2010). One, four, and seven are the cut points for mild, moderate, and high disability, respectively. A total score of 25 or more indicates a general high disability, and the patient will be asked by a clinical psychologist to confirm: 'Are you on sick leave?', 'Can you do the housework?', and 'Can you engage socially?' (one question per area).

Psychological, physical, social, and environmental domains will be assessed through the twenty-six 5-point Likert items of the WHOQOL-BREF (The WHOQOL Group, 1998b), the abbreviated version of the 100-item WHOQOL (WHOQOL-100) (The WHOQOL Group, 1998a). The more the participant scores, the better quality of life they have. The WHOQOL has been validated with Spanish population (Lucas-Carrasco, 2012; Rocha et al., 2012) and has shown good psychometric properties: α > .7 in psychological, physical, and environmental domains, though social domain's internal consistency varies from .58 (Rocha et al., 2012) to .75 (Lucas-Carrasco, 2012).

The RRS (Nolen-Hoeksema & Morrow, 1991) was originally developed to measure the ruminative responses to depressed mood. It has been validated with Spanish population (Hervás, 2008), however, only the 5-item 'brooding' factor subscale (RRS-B) will be used in this trial (α = .79) (Muñoz-Navarro et al., 2021). The RRS-B scores from 1 ("almost never") to 4 ("almost always") how often the participant thinks as it is described in each item when they are discouraged, sad or depressed.

The PSWQ (Meyer et al., 1990) measures the pathological worry as an uncontrollable and general state (i.e., as a GAD feature). It has been validated in Spain (Sandín et al., 2009) and, in this study, it will be used an 8-item abbreviated version (PSWQ-A) (Crittendon & Hopko, 2006) that has already showed good properties in primary care (α = .9) (Muñoz-Navarro et al., 2021). The PSWQ-A items rate how much worries affect the person from 1 ("not at all typical of me") to 5 ("very typical of me").

The IACTA was originally developed by Cano-Vindel (2001). It includes subscales that assess distortions according to Eysenck's four-factor theory (Eysenck, 2000). The abbreviated panic version (IACTA-PB; α = .87) (Muñoz-Navarro et al., 2021) will be used to measure attentional biases. It specifically scores from 0 ("almost never") to 4 ("almost always") how often the participant has certain cognitive distortions. The Questionnaire of Cognitive Distortions in Emotional Disorders (CDTE) (The PsicAP Group, unpublished) scores from 0 ("almost never") to 4 ("almost always") the frequency of certain cognitive biases in the main EDs (MDD, GAD, PD, and somatization disorder). It includes 16 items that measure the presence of four factors: sustained attention bias (α = .96), divided attention bias (α = .95), magnification interpretational bias (α = .94), and catastrophization interpretational bias (α = .96), with high levels of discriminant validity among the four EDs (ROC values > .8).

The CERQ-36 (Garnefski et al., 2001) was developed for measuring the specific cognitive emotion regulation strategies that a person uses to face a stressful event. It scores from 1 ("almost never") to 5 ("almost always") how often the participant thinks as described. The CERQ has been validated with Spanish population (Domínguez-Sánchez et al., 2013) and the 27-item shortened version (Holgado-Tello et al., 2018) will be used (α values range from .72 ['acceptance'] to .88 ['positive refocus']).

The MCQ-30 (Wells & Cartwright-Hatton, 2004) is a short form of the original MCQ (Cartwright-Hatton & Wells, 1997), which measures the beliefs about the own thinking processes. It has been validated with Spanish population (Ramos-Cejudo et al., 2013) and, in the current trial, only the 6-item 'negative beliefs' (about uncontrollability/danger) subscale (MCQ-NB; α = .82) will be used (Muñoz-Navarro et al., 2021). It scores from 1 ("totally disagree") to 4 ("totally agree") how the patient agrees with the sentences written.

An ad hoc questionnaire will be used to collect sociodemographic (gender, age, civil status, educative level, employment situation, and income level) and ED-related medical data (public and private health care consultations, accidents, medical tests, and sick leaves in the past 3 months; psychotropic drugs or other medication, and their posology), and it includes an additional question about treatment satisfaction (only at post-treatment and follow-ups). Medical records will be also consulted to complete the information (for privacy reasons, only strictly necessary data will be collected).

The medical data collected will be used for cost calculations too. In addition, cost-utility will be measured through the European Quality of Life Scale (EuroQoL, EQ) (The EuroQol Group, 1990). The Spanish version of the 5-domain, 5-level EuroQol (EQ-5D-5L) (Badia et al., 1999; van Reenen et al., 2019) will be used to calculate the quality-adjusted life years (QALYs). The EQ-5D-5L measures five domains of health-related quality of life (mobility, self-care, daily activities, pain/unease, and anxiety/depression) through 5 severity levels ("no problems", "slight problems", "moderate problems", "severe problems", and "extreme problems"), being able to stablish up to 3125 different health states, each of which can be represented through an index value that reflects the health state quality contextualized in the person's country/region. It also includes a visual analogue scale (VAS) that scores from 0 to 100 the current subjective, general health state.

The PHQ also lets to measure the presence of other mental disorders. The Spanish version (Díez-Quevedo et al., 2001) detects eating disorders, such as bulimia nervosa or binge eating disorder, with a sensitivity of 92% and a specificity of 98%; and alcohol abuse with a sensitivity of 76% and a specificity of 99%. Affirmative answers to items 6a to 6c and 8 indicate bulimia nervosa; if item 8 were answered negatively (or unanswered), it would point out a binge eating disorder. An affirmative answer to any of the items 10a to 10e would indicate alcohol abuse. In any of these cases the patient would be interviewed by a clinical psychologist to confirm a possible diagnosis of eating, alcohol or personality disorder.