Classification tests

6.2.2.2.1Structured Interview Guide for the Hamilton Depression and Anxiety Scales (SIGH-AD)

The SIGH-AD is a combination of the Structured Interview Guide for the Hamilton Depression Rating Scale (SIGH-D) (Hamilton, 1960) and the Structured Interview Guide for the Hamilton Anxiety Scale (SIGH-A) (Hamilton, 1959). SIGH-

AD measures depression and anxiety severity and consists of 31 questions: 17 measure depression severity and 14 measure anxiety severity. The output has two scores, one for depression severity and the other for anxiety severity. The experimenter read each question and sub-question to the participant. For example, Question 1 was, ‘What’s your mood been like this week?’ Below the question were a series of sub-questions such as. ‘Have you been feeling down or depressed?’ and ‘How are you feeling about the future?’ Adjacent to the question and sub-questions was an indicator of what the

question was measuring and a number scale with a worded description corresponding to each number. For the above question, the item to be measured was ‘depressed mood (sadness, hopeless, helpless, worthless)’. Under the statement, the numbers 0–4 contained the following worded descriptions: (0) absent; (1) indicated only on questioning (occasional, mild depression); (2) spontaneously reported verbally (persistent, mild to moderate depression); (3) communicated non-verbally; i.e., facial expression, posture, voice, tendency to weep (persistent, moderate to severe

depression); (4) virtually only those feeling states reported in spontaneous verbal and non-verbal communication (persistent, very severe depression, with extreme

hopelessness or tearfulness). With the aid of the worded descriptions, the investigator chose a numbered answer to match the participant’s answer (see Appendix A). These descriptions were taken from the Early Clinical Drug Evaluation Program Assessment Manual (Guy, 1976). SIGH-D was developed to improve the reliability of the Hamilton Depression Rating Scale. Reliability information for the SIGH-D can be found in Williams (1988). The Structured Interview Guide for the Hamilton Anxiety Scale (SIGH-A) has been shown to have high test–retest reliability and interrater reliability and good validity when compared to the Beck Anxiety Inventory (Shear et al., 2001). In the current study, overall the SIGH-AD had good internal consistency with a Cronbach

alpha coefficient of .95. With the scale split into the two individual scales, SIGH-D and SIGH-A, the Cronbach alpha coefficient was .88 and .91 respectively.

6.2.2.2.2Centre for Epidemiologic Studies Depression Scale (CES-D)

The CES-D is a depression severity self-report scale designed to measure depressive symptomology in the general population (Radloff, 1977). The CES-D consists of 20 questions that aim to elicit how the individual felt or behaved in the last week. For each question, the participant chooses between four periods such as (a) none of the time, (b) some of the time, (c) a moderate amount of time and (d) most of the time. Selection (a) scores 1, (b) scores 2, (c) scores 3 and (d) scores 4, except for questions 4, 8, 12 and 16, which are reversed scored. The total is then added. Scores below 15 indicate that the person is not suffering from depression. Scores 15 to 21 indicate the person may be suffering from mild to moderate depression and for scores 22 or higher, the person may be suffering from major depression (see Appendix B) (Radloff, 1977). CES-D has very high internal consistency and adequate test–retest repeatability, with a coefficient alpha of approximately 0.85 for the general population sample and 0.90 for a psychiatric (depression) patient sample (Radloff, 1977). The CES-D also correlates moderately with the Hamilton Clinician’s Rating Scale at patient admission (.44 to .54) and higher after four weeks of treatment (.69 to .75) (Radloff, 1977). In the current study, the Cronbach alpha coefficient was .94.

6.2.2.2.3Mini International Neuropsychiatric Interview English version 5.0.0 (MINI PLUS)

The MINI PLUS was used to obtain medical diagnostic material to categorise participants by medical disorder (Sheehan et al., 1998). The MINI PLUS is a short, structured diagnostic interview that takes approximately 15 to 20 minutes to administer (Pinninti, Madison, Musser, & Rissmiller, 2003) (see Appendix C). Structured

diagnostic paper tests are more advantageous than a clinical diagnosis, as clinical diagnoses have been found to be unreliable, owing to diagnostic disagreements between clinicians (Pinninti et al., 2003). Substantial inconsistencies between clinicians have been found to be due to the context surrounding the diagnosis and the type of professional (Kirk & Hsieh, 2004). An advantage of the MINI PLUS is that it is structured to allow interviewing by non-specialised interviewers (Lecrubier et al., 1997).

The MINI PLUS was chosen over the standard Mini International

Neuropsychiatric Interview (MINI), as it included additional items including pain disorder and premenstrual dysmorphic disorder. To compare the validity and reliability of the MINI PLUS, the MINI was instead used. This was because first, there is limited validation data for the MINI PLUS specifically and second, the additional items in the MINI PLUS were not essential to this study. The MINI was validated through

comparisons with known diagnostic tests, such as the Structured Clinical Interview for the DSM-III-R (SCID-P) and the Composite International Diagnostic Interview, and it scored highly in interrater and test–retest reliability studies. The MINI compared favourably to the SCID-P (Sheehan et al., 1997), the Composite International Diagnostic Interview (Lecrubier et al., 1997) and to diagnosis in a clinical setting (Pinninti et al., 2003). The MINI demonstrated excellent interrater reliability with all kappa values greater than .7 (Lecrubier et al., 1997; Sheehan et al., 1997). It showed very good test–retest reliability, with one study showing that 14 of 23 items had kappa values greater than .7 (Sheehan et al., 1997) and a second study showing kappa values ranging from .76 to .93 (Lecrubier et al., 1997).

6.2.2.2.4Psychiatric and medical questionnaires

Psychiatric and medical questionnaires (Appendices D & E) were utilised to obtain further relevant information such as family history and past and present medical conditions. The questionnaires examined whether the participant had received any medical diagnosis, number of depressive episodes in the past year and information regarding hospitalisation and suicidality. It also recorded the participant’s past medical diagnosis and whether family members had received a medical diagnosis of MDD, bipolar disorder or schizophrenia.