Development and reliability of a structured interview ...

1 Observer-rated depression rating scales are used in clinical trials ofantidepressants to select patients for study, and to assess theefficacy of the treatment being tested. The importance of thequality of ratings in clinical trials has recently been evidence suggests that the quality of ratings canmake the difference between a failed trial and one in which drugseparates from , any method that improves thequality of clinical trial ratings may improve our ability to conductsuccessful antidepressant trials. We describe the Development ofa structured interview guide for the Montgomery A sbergDepression Rating scale (MADRS) and its test retest reliability ,assessed in a sample of 51 persons with varying levels of A sberg depression Rating ScaleThe MADRS was developed in the late 1970s from items that werefound in several studies to be sensitive to change with anti-depressant its publication the scale has becomeincreasingly popular worldwide.

2 Dissatisfaction with the leadingalternative, the hamilton Rating scale for depression (HRSD),has further contributed to the popularity of the importance of reliability of assessments in a clinical trialcannot be overestimated. Without good interrater agreement thechances of detecting a difference in effect between drug andplacebo are significantly reduced. Muller & Szegedi demonstratedthat as the reliability of a rating scale decreases from to , thepower of the test to detect a significant difference between drugand placebo drops from 71% to 51%, increasing the risk of typeII general, total scale score reliability of the mostcommonly used depression rating scales such as the MADRSand HRSD is high, with or without the use of a structured inter-view ,6 However, as compounds have become targeted tospecific symptoms and clinical trials have revealed specific drugs effects on clusters of symptoms,7,8it has become more importantto be able to depend on the reliable measurement of an individualsymptom or a subgroup of symptoms.

3 Self-report versions ofclinician-administered scales have been developed9,10that showhigh degrees of correlation with the clinician versions; however,there are limited empirical data on their signal detection relativeto the clinician in placebo-controlled is minimal information available concerning the inter-rater reliability of the MADRS. The original article4reportedexcellent agreement between rater pairs, but only as conjoint reliability , and in only 11 patients. Maieret alreported total scoreintraclass coefficients (ICCs) of , and in threeseparate samples, using joint interviews in the first sample, andindependent interviews in the second and third samples (whichwere actually the same patients pre- and post-treatment).11 Unfortunately item reliability was not provided, although theauthors did report that three of the MADRS items (inner tension,lassitude and suicidal thoughts) had ICCs lower than in allthree samples.

4 Davidsonet altested the reliability of the MADRSin 44 people receiving in-patient treatment for depression , usingan experienced research nurse and a psychiatrist as joint agreement was acceptable and ranged from fair to good on individual items. More recently, a Japaneseversion was developed and tested in Japan in joint interviews ona sample of seven patients with DSM IV major depressive ICCs were in the very good to excellent range; however, the weakness of the testing method (small samplesize and repeated assessment of the same patients by the samethree raters in joint interviews) compromised the significance ofthe results. Therefore, there is reason to believe that the interraterreliability of the MADRS in a typical research study could MADRS was originally published without suggested ques-tions for clinicians to use in gathering the information necessaryto rate the ten items. However, several studies have found thatusing a structured or semi- structured interview guide improves52 Development and reliability of a structuredinterview guide for the Montgomery A sbergDepression Rating scale (SIGMA)Janet B.

5 W. Williams and Kenneth A. KobakBackgroundThe Montgomery A sberg depression Rating scale (MADRS) is often used in clinical trials to select patientsand to assess treatment efficacy. The scale wasoriginally published without suggested questions forclinicians to use in gathering the information necessary torate the items. structured and semi- structured interviewguides have been found to improve reliability with describe the Development and test retest reliabilityof a structured interview guide for the MADRS(SIGMA).MethodA total of 162 test retest interviews were conducted by 81rater pairs. Each patient was interviewed twice, once byeach rater conducting an independent intraclass correlation for total score between ratersusing the SIGMA wasr ,P< All ten items hadgood to excellent interrater of the SIGMA can result in high reliability of MADRS scores in evaluating patients with of interestNone. Funding detailed in British Journal of Psychiatry(2008)192, 52 58.

6 Doi: on similar rating ,15 Moberget alcomparedindependent interviews using the standard unstructured HRSD with the structured interview Guide for the HRSD (SIGH D)and concluded that the SIGH D produced uniformly higheritem- and summary scale reliabilities than the unstructuredHDRS .16 Further, in one placebo-controlled antidepressant trial,raters who more closely adhered to a semi- structured interviewguide were found to have better signal detection than raterswho did an interview guide provides some assurancethat raters across clinical trial sites administer the scale in approx-imately the same way. structured interview guides also facilitatetraining in the use of a scale by providing new raters with explicitinstructions and specific interview questions that have beenderived from expert interviews. structured interview guides havebecome fairly standard for diagnostic interviews,16as well as formany rating scales, including the hamilton scales for depression (SIGH D)14and anxiety (SIGH A).

7 17,18In general, they aredesigned to approximate an expert administration of the of SIGMA probes and conventionsA semi- structured interview guide similar to the SIGH D wasoriginally developed by for the MADRS in 1988 andhas undergone several revisions since then, based on user ex-perience and feedback from raters. More recently, joinedas co-author in a major overhaul of the interview guide. TheStructured interview Guide for the MADRS (SIGMA) providesstructured probes to ensure standardisation of administrationand comprehensiveness of coverage of the ten items of the SIGMA questions were developed to obtain the informationneeded to assess each of the items anchor points (see Appendix).Each item begins with questions in bold type that should be askedexactly as written. Often these questions will elicit enough infor-mation about the severity and frequency of a symptom for theitem to be rated with confidence.

8 Follow-up questions are pro-vided, however, for use when further exploration or additionalclarification of symptoms is necessary. The specified questionsshould be asked until the rater has enough information to ratethe item confidently. Raters are also encouraged to add theirown probes as necessary to obtain enough information to rateeach item the SIGMA the original MADRS appears on the right-handside of the page and the structured interview guide questionsappear on the left. The interview guide begins with the overview ,which is a brief explanation of the time period to be covered, andinitial questions to allow some rapport to develop and to give theinterviewer some sense of the context of the interviewee s currentsituation. The interview guide then follows, with questions foreach of the ten MADRS the SIGMA the only change that was made to the originalMADRS was to reverse the order of administration of the first twoitems (apparent sadness and reported sadness).

9 There was consen-sus from users that asking about reported sadness first made for amore logical flow to the interview . Direct probes were added to theapparent sadness item to supplement the rater s observation ( In the past week, do you think you have looked sad or depressedto other people?) The rationale for these additional probes wasthat without the aid of an informant who has seen the patient overthe past week it is difficult to rate the persistence and depth of thisitem based on observation during the interview alone. This tech-nique has been used successfully in self-report and telephone-administered versions of the MADRS,10,19as well as in compu-terised and paper-and-pencil self-report versions of the HRSD20,21and the hamilton Rating scale for are instructedto consider both sources of information (direct observation andself-report) in rating this the interview guide there is an emphasis on open-endedquestions, to encourage respondents to describe their experiencein their own words, and to avoid raters putting words in the per-son s mouth.

10 Thus, for example, instead of asking the person atthe beginning of the interview , Have you been feeling sad or un-happy? , the enquiry begins, How have you been feeling since last[day of week]? Likewise, instead of asking whether the person hashad trouble sleeping in the past week, the sleep item begins, Howhas your sleeping been in the past week? Some items are assessedmore directly, to improve the efficiency of the interview . For manyresponses the person is asked to provide examples; for instance, ifthere is a positive response to the question, Have you had troubleconcentrating or collecting your thoughts in the past week? theinterviewer is instructed to ask, Can you give me some examples? Once the person has described the symptom in his or her ownwords, the interviewer can then decide whether concentrationdifficulty is truly present, which would be rated in this the revised SIGMA was completely drafted, revisionswere made based on feedback from a number of users in the field,and the instrument was finalised.