A CLINICIAN-ADMINISTERED SEVERITY RATING SCALE FOR ILLNESS ANXIETY: DEVELOPMENT, RELIABILITY, AND VALIDITY OF THE H-YBOCS-M

Hypochondriasis is characterized by preoccupation with the fear or belief of having a serious disease, based on a misinterpretation of normal bodily symptoms that persists despite medical reassurance.[1] It exerts a heavy toll on the afflicted individuals and on national health-care resources.[2, 3] It is also a common disorder in the primary care population in the United States, with an estimated prevalence of 4%.[4] In the last decade, hypochondriasis (also referred to as health anxiety or illness anxiety) has received increased research attention, both phenomenologically and therapeutically.[5–7] However, the lack of consistently used and validated clinician-administered measures limits researchers’ ability to adequately assess severity and treatment effectiveness.[8] Currently, there are two widely used well-validated, self-report measures of hypochondriasis severity: the Whiteley Index[9] and the Illness Attitude Scale.[10] These measures, although excellent for assessing illness-related cognitions and fears, do not adequately assess other important features of hypochondriasis—such as illness-related behaviors (e.g., reassurance seeking) and illness-related avoidance. In the assessment of the severity of other disorders characterized by obsessional thoughts, clinician-administered measures have been developed that examine not only repetitive thoughts but also the behaviors conducted in response to these thoughts. These sensitive and reliable instruments—such as the Yale-Brown Obsessive Compulsive Scale (Y-BOCS)[11, 12] to assess obsessive-compulsive disorder (OCD) and the BDD-YBOCS[13] to assess body dysmorphic disorder—quantify the impact of obsessive thoughts and behaviors not by evaluating the symptom’s idiosyncratic content but by assessing thoughts and behaviors along the dimensions of duration, functional interference, distress, and the degree to which the patient can resist or control the symptoms. Neither the Whiteley Index nor the Illness Attitudes Scale assesses all of these dimensions. More recently, the psychometric properties of a clinician-administered instrument for assessing hypochondriasis (the H-YBOCS) were published.[14] As the first validated, clinician-administered instrument to assess illness anxiety, this scale represents a significant advance in the field. The H-YBOCS was modeled after the Y-BOCS and therefore assesses symptoms by examining time, distress, resistance, control, and functional interference. Because both OCD and hypochondriasis share similar phenomenology (obsessive thoughts and compulsive behaviors), the use of the Y-BOCS as a model for the development of a measure of illness anxiety was a logical step.[15, 16] Although the H-YBOCS retains the dimensional format of the original Y-BOCS, it also expands upon the Y-BOCS by including item clusters that measure not only obsessive thinking and compulsive behavior, but also avoidance. This article reports on the psychometric validation of a modified version of the H-YBOCS, termed as the H-YBOCS-M. Because of the close similarity between the two instruments, this report should be considered both a replication and extension of the initial psychometric article on the H-YBOCS.[14] The extension in this reports refers to: (a) a comparison of the sensitivity to change for the H-YBOCS-M with measures of change on other dimensions of psychopathology; (b) the determination of whether a measure of quality of life relates to either baseline or change scores on the H-YBOCS-M; and (c) a psychometric assessment of this revised version that includes new items and a new self-report component (a Symptom Checklist). Both the Checklist and the Questionnaire are included in the Appendix. Our prior research[7] used an unpublished hypochondriasis-modified version of the Y-BOCS (labeled CHIC-OCS—“Columbia Heightened Illness Concern-Obsessive Compulsive Scale”). The H-YBOCS and H-YBOCS-M represent an improvement on the CHIC-OCS by including a major section on avoidance behaviors. One feature of hypochondriasis that neither the original H-YBOCS nor the CHIC-OCS was designed to measure however was the waxing and waning quality of illness-related anxiety. Unlike the intrusions and compulsions in OCD that are typically a daily experience, the illness worries and behaviors of the hypochondriacal patient can have a wider range of frequency—from daily to less than once a week. Therefore, to enhance the measurement of illness anxiety severity, our revised instrument (i.e., H-YBOCS-M) has added items that specifically assess frequency (number of days per week in which there are illness-related worries, behaviors, or avoidance). Five additional modifications distinguish the H-YBOCS-M from the H-YBOCS. First, retaining the convention in the original Y-BOCS, the insight item of the H-YBOCS-M is considered an independent item and is not included in the calculation of the total severity score. Second, to help the interviewer identify the most prominent manifestations of illness anxiety, a self-report Checklist has been added to the H-BOCS-M that itemizes many common illness-related obsessions, compulsions, and avoidance behaviors; a similar checklist approach guides the interviewer in the use of the Y-BOCS for OCD and was used in the CHIC-OCS. Third, because patients with health anxiety view the term “hypochondriac” as pejorative, the H-YBOCS-M has replaced the term “hypochondriacal” with phrases that ask about fears of “illness” or “a serious disease.” This terminology is also consistent with the changes proposed for the Somatic Symptom Disorder section of DSM-5 in which the term hypochondriasis is replaced by such terms as “illness anxiety” and “health anxiety.”[17] Fourth, in the assessment of distress associated with illness-related behaviors, the H-YBOCS-M phrases the question quite differently from the H-YBOCS. Because reassurance seeking in hypochondriasis is often ego-syntonic and experienced at least temporarily as a source of relief, this item in the H-YBOCS-M is phrased to assess the degree of distress that would arise if checking and reassurance-seeking behaviors were prevented, whereas in the H-YBOCS, the corollary question asks about distress associated with seeking of reassurance itself. Finally, the H-YBOCS-M adds an instructional section to assist in the assessment of avoidance and an item asking about the number of situations that the patient currently avoids.