Psychiatric Interview, The: Practical Guides in Psychiatry
2nd Edition

19
Interviewing for Diagnosis: The Art of Hypothesis Testing
The problem is how to come up with a complete and accurate diagnosis in a very limited amount of time. Early in training, this is less of an issue, when you are encouraged to spend what you will later consider to be inordinate amounts of time interviewing your patients. But after training, you will quickly realize that there is a correlation between the number of patients that you see per day and your ability to afford a mortgage on that new home. You will be torn between the need to do things quickly and the need to do things right.
The way things are done in most busy community clinics is probably not so “right.” One recent study compared “routine diagnoses” as found in the medical chart with a “gold standard diagnosis” generated using the SCID [Structured Clinical Interview for Diagnostic and Statistical Manual of Mental Disorders, Revised Third Edition (DSM-III-R)] plus chart review as well as an additional interview with a highly qualified psychiatrist or psychologist. There was only about a 50% rate of agreement between routine and gold standard diagnosis, and in one-half of all cases of disagreement, feedback to the original clinicians resulted in significant changes in patient care.
Does this mean that you should give the SCID to all of your patients before the interview? Thankfully not, because the techniques discussed in this section, involving screening and probing questions, mirror the SCID gold standard, adapting it to the realities of clinical practice.
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One might assume that the best way to reach a diagnosis is to follow a two-step process:
  • Obtain all potentially relevant data about the patient.
  • Examine the data to determine which diagnosis fits best.
This strategy would work well if time were limitless. Because it isn’t, clinicians have developed ways of determining in advance what is likely to be relevant data for a particular patient, thereby vastly increasing the efficiency of the diagnostic interview.
How do expert clinicians make diagnoses? A number of researchers have done observational studies to answer this question (Elstein et al. 1978; Kaplan 1995). They have found that experienced clinicians begin by carefully listening to the patient’s initial complaint and asking open-ended questions. Based on this preliminary information, they generate a limited number of diagnostic hypotheses (the average being four) early in the interview, usually within the first 5 minutes. They then ask a number of closed-ended questions to test whether each hypothesis is true. This process is known as pattern-matching, in which the patient’s pattern of symptoms is compared with the symptom pattern required for a diagnosis.
Another way to view this approach is to think of a “closed cone” of questions (Lipkin 1987). The initial questions are open ended and exploratory; they become more closed ended to pursue a specific diagnosis to an endpoint of verification or exclusion.
In accordance with these research-based conceptions, I suggest the following four stages for rapidly establishing diagnoses during the psychiatric interview.
FREE SPEECH PERIOD
In Chapter 3, I emphasize the value of giving the patient the opening word as a way of helping to create a therapeutic alliance, but it’s also valuable for beginning the process of generating hypotheses. Generating diagnoses begins the moment you first see your patient and continues throughout the interview. It’s important that your mind should be especially active during the first few minutes.
Keep the mnemonic “Depressed Patients Sound Anxious, So Claim Psychiatrists” in mind as you listen to your patient. Does she appear depressed or manic? Is she speaking coherently, and is her reality testing good? Does she seem anxious? Does she
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seem sharp or cognitively impaired? Is she beginning the interview complaining of numerous somatic symptoms? Does she have alcohol on her breath? Does she seem inappropriately angry or entitled? You will quickly be able to generate a mental list of likely diagnoses, which you should follow up on later in the interview with appropriate screening and probing questions.
SCREENING AND PROBING QUESTIONS
Once you’ve generated your short list of likely diagnoses, go on to test your hypotheses. Begin by asking a screening question that gets at the core feature of the disorder. Each disorder-specific chapter in Section III suggests one or more screening questions. For instance, a screening question for bipolar disorder (see Chapter 23) is
Have you ever had a period of a week or so when you felt so happy and energetic that your friends said that you were talking too fast or that you were behaving differently and strangely?
If the patient answers “yes,” go right into the mnemonic for manic episodes (DIGFAST) and ask primarily closed-ended questions about each criterion. If the patient answers “no” and you are certain that he understood the question, you should conclude that bipolar disorder is unlikely and move onto another part of the interview.
Interviewing for diagnosis is an active, probing process in which you will often do as much talking as your patient. Is such an active style really more effective in eliciting diagnostic information than a quieter, listening style? Common sense dictates that it is, and the Maudsley Hospital researchers concluded that it is as well. In one of their papers examining techniques for eliciting factual information (Cox et al. 1981b), they found that a focused and directive style, in which interviewers used many probing questions and often requested detailed information, led to better data than a more passive style. The best data were obtained when interviewers used at least nine probing questions per symptom. Data were judged to be “better” when, in addition to the mere mention of a symptom, such as depression, interviewers could obtain information about the frequency, duration, severity, context, and qualities of the symptom, all of which are extremely important for diagnostic decision making.
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The concern remains that a directive style may elicit great factual data at the expense of shutting the patient down emotionally with too much questioning and not enough listening. Cox et al. (1981a) examined this issue and found that more directive interviewers actually elicited slightly more feelings than did interviewers with a less directive style.
TRANSITION GRACEFULLY TO DIAGNOSTIC QUESTIONS
Illustrative Transitions to Diagnostic Areas
  • Depression
    With things so bad in your marriage, I wonder how it’s been affecting your mood.
  • OCD
    You said you’re often late. Are there rituals you do at home that make you late, like checking or cleaning things?
  • Substance abuse
    Given all the stress you’ve been under, do you have a drink now and then to deal with it?
  • Suicidality
    With things going so poorly in your life, I wonder if you’ve been debating whether it’s worth it to go on?
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  • Borderline personality disorder
    Earlier you mentioned that your husband left you years ago; how do you normally deal with rejection?
  • Psychosis
    You’ve been through so much stress lately—does it ever cause your mind to play tricks on you, so that you hear voices or have strange ideas?
PSYCHIATRIC REVIEW OF SYMPTOMS