Most medical reliability research, including previous DSM reliability studies, have relied on interrater reliability—two independent doctors evaluating the same X-ray or interview, for example. While interrater kappa values between 0.6 and 0.8 are seen on occasion, the more usual range is between 0.4 and 0.6. (4, 5). The most recent study conducted by the DSM-5 Work Group to assess diagnostic reliability found that overall agreement among members of the work group was good but not perfect. They concluded that the new system's reliability would be sufficient for use with clinical populations.
The work group based their conclusion on data from four studies. The first study involved evaluation of nine psychiatric diagnoses by six separate groups of two judges per diagnosis. Overall agreement ranged from fair to excellent for all diagnoses except bipolar disorder, where it was only good. The second study involved assessment of eight different physical conditions by five separate groups of two raters per condition. Again, overall agreement was only good for bipolar disorder, and only one diagnosis reached the threshold for acceptable reliability (k = 0.6). The third study evaluated the consistency of symptom severity ratings across three time points for 106 individuals with schizophrenia. Agreement was good for positive symptoms but only moderate for negative symptoms. The final study examined the concordance between diagnoses assigned by clinicians using the old and new systems. Overall agreement was high for both major depressive disorder and anxiety disorders, but lower for substance use disorders and personality disorders.
Although psychiatric diagnoses have been more accurate and valid since the publishing of DSM-III (Klerman, 1984; Spitzer et al., 1979), present findings, together with those from the DSM-5 Field Trials, imply that psychological diagnosis reliability may be lower than popularly assumed. The new system is expected to improve diagnostic accuracy by reducing the number of categories and allowing for greater specificity in diagnosis.
DSM-IV was developed as a comprehensive language for describing psychiatric disorders. It is an objective tool used to classify individuals who show signs of distress or impairment within a clinical setting. The advantage of this classification system is that it allows for close comparisons to be made between cases, which aids in understanding how different factors are associated with particular disorders. Disadvantages include its exclusive focus on behavioral and cognitive symptoms, and the fact that it can be difficult to apply to patients who do not seek medical help.
Since its creation in 1952, the DSM has become the "bible" of psychiatry, providing detailed descriptions of each disorder and its corresponding treatments. Although this book is constantly being updated, any new diagnosis or description of a disorder found in it becomes part of the permanent record known as the DSM-5.
As you can see, the DSM is very useful for comparing cases of mental illness and their treatments. However, it is not perfect. There are several problems with relying solely on this classification system to describe all aspects of human behavior.
The DSM-5 merged the first three axes into one to eliminate what are now considered arbitrary differences between diagnoses. It is also envisaged that this may aid physicians, researchers, and insurance companies in the organization of data. The most important change made by the DSM-5 is the elimination of the term "disorder" from the title of these categories instead referring to them as "Conditions".
Axis I of the DSM-5 is called Clinical Syndromes. It consists of 26 clinical conditions that psychiatrists have found useful in describing how people think and act. These conditions are: anxiety disorders; attention-deficit/hyperactivity disorder (ADHD); bipolar disorder; borderline personality disorder (BPD); chronic fatigue syndrome (CFS); depression; eating disorders; fetal alcohol spectrum disorders (FASD); fetal brain abnormalities; gambling disorder; obsessive-compulsive disorder (OCD); oppositional defiant disorder (ODD); panic disorder; pedophilia; post-traumatic stress disorder (PTSD); schizophrenia; sexual dysfunctions; substance abuse disorders; trichotillomania (hair-pulling disorder); and other specified disorders not elsewhere classified.
Axis II of the DSM-5 is called Severity Levels. They consist of four categories: mild, moderate, severe, and extreme. Within each category, there are different subtypes or diagnostic groups.
The DSM-IV-TR includes diagnostic criterion sets to assist clinicians in making the accurate diagnosis, as well as a section devoted to differential diagnosis when persons fulfill diagnostic criteria for more than one illness. The four major categories of disorders include mental illnesses, developmental disabilities, substance use disorders, and behavioral syndromes.
Mental illnesses are conditions characterized by abnormal thoughts, emotions, or behaviors that cause significant distress or impairment in social functioning. Examples include anxiety disorders, attention-deficit/hyperactivity disorder (ADHD), bipolar disorder, depression, and schizophrenia. Developmental disabilities are chronic conditions that affect brain development. They can be physical, such as cerebral palsy, or cognitive, such as intellectual disability or autism. Substance use disorders are patterns of behavior marked by excessive use of alcohol or other substances that result in negative effects for the user. Behavioral syndromes are long-term problems that affect a person's mood, behavior, and ability to function daily life tasks. They often begin in childhood and continue into adulthood. Examples include obsessive-compulsive disorder (OCD) and tic disorders.
Each mental illness and developmental disability has its own set of symptoms and treatment guidelines. However many people suffer from more than one mental illness at a time. For example, someone may have symptoms of depression and also have ADHD. When this occurs, it is called comorbidity.
If diagnostic reliability is defined as the likelihood of a patient receiving the same diagnosis at different hospitals or clinics, or the likelihood of different studies recruiting similar patients, then the test-retest method provides a more meaningful estimate of diagnostic reliability (Kraemer et al.). The kappa statistic is used to measure interrater agreement for categorical data. It ranges from -1 to +1, with 0 indicating no agreement beyond chance and 1 perfect agreement. A kappa value of 0.8 or higher is considered good agreement.
Kappa can be calculated using Stata's "kappas" command. For example, let's say that patients were asked whether they had diabetes by way of a questionnaire administered at both visits. If 20% of patients answered yes at visit 1 and 15% at visit 2, then the kappa would be 0.76. Kappas are useful in comparing results across studies but should not be interpreted in isolation. For example, if one study found a kappa of 0.75 while another found only 0.4, it may be because the first study included cases where agreement was high while the second included cases where agreement was low. There are several other statistics that can be used to measure reliability. Two commonly reported measures are sensitivity and specificity. Sensitivity refers to the ability of a test to identify those patients who actually have the disease; specificity refers to the ability of a test to avoid identifying those patients who do not have the disease.
Which is not a critique of DSM-5 personality disorder diagnoses? Either problematic personality characteristics are present or missing. Only $3.99 each month. Diagnostician A places an individual's personality disorder in the "odd" cluster based on a systematic interview. Diagnosticians must use the same classification system in order to compare results between studies. Although interrater reliability for specific traits has been reported to be good, this does not mean that one rater can accurately identify these traits in another person. Interrater reliability would be expected to decrease if multiple clinicians tried to assign a single patient to more than one category.
Critiques of the DSM 5 personality disorder diagnoses include: (1) It is likely that many people get multiple personality disorders (or some other type of mental illness) from time to time. It is difficult or impossible to tell how many people have this problem without looking at past reports on the topic. (2) The criteria used by the DSM-5 to diagnose personality disorders are very strict. This means that a lot of people will be diagnosed with a personality disorder who do not need to see their doctor. (3) The criteria used by the DSM-5 to diagnose personality disorders focus on what people do rather than on what goes on inside their minds. This means that someone can get a personality disorder diagnosis even if they feel sad sometimes or act in ways that are inappropriate given their circumstances.