Journal of Rural Community Psychology Volume E9 Number 1 Spring 2006
Prevalence of Personality Disorders at a Rural State Psychiatric Hospital
Abe Adel, Geoffrey Grimm, Neil L. Mogge
West Virginia University, School of Medicine
William R. Sharpe, Jr. Hospital
& Tracy Sharp
West Virginia University
While prevalence rates of personality disorders have been previously studied, methodological consistency has not been a clear focus. This has led to limitations of comparison due to wide-ranging types of sample, measures, and patterns of analysis. The present study focuses on the discharge diagnoses of involuntarily committed patients released from a rural state psychiatric hospital during a three-year period. The purpose was to identify the prevalence of personality disorders (PD’s) and their demographic correlates. A secondary purpose is to address the different ways researchers have identified prevalence rates, and the differences in conclusions that resulted depending on the pattern of analysis. I was found that overall trends were relatively consistent with trends found in other populations, but that specific findings varied based on the pattern of analysis.
Personality disorders (PD) are complex, chronic disorders that present significant clinical challenges. With the possible exception of Antisocial Personality Disorder, prevalence rates of personality disorders have not been studied extensively, and most existing studies are community-based. They have pointed to a range of personality disorders of 5.9% to 31.2%, with 10% being considered representative of the “true” rate in the general population (Lyons & Jerskey, 2002).
Review of the literature reveals limitations in comparing results among previous studies, possibly due to variability in types of populations, measures, and patterns of analysis. This was demonstrated by widely differing prevalence rates of personality disorders. For example, Casey, Tyer, & Dillon (1984) found a 34% rate, Casey, Tyer, & Platt (1985) a 20% rate, Dahl (1986) 45%, and Oldham & Skodol (1991) found a 10.8% rate. This pointed to an average prevalence of personality disorders in clinical populations of approximately 27%.
With regard to measures, researchers tended to use various screening instruments. Some were not based on common diagnostic criteria, and others that were, used abbreviated criteria sets (Weissman, M., 1993) & (Lyons, M. & Jerskey, B., 2002). There were no studies identified that used repeated observations over time in a structured clinical setting. With regard to patterns of analysis, review of the literature revealed that there were several different ways of counting diagnoses. One method was totaling consecutive contact events as though each represented a separate diagnosis. The second pattern was to count each individual only once, regardless of how many personality disorder diagnoses they carried. In a third pattern, individuals with multiple personality disorder diagnosis were counted multiple times, once for each diagnostic category. Others clustered the multiply diagnosed individuals into a separate category. There was also difficulty separating multiple personality disorder diagnoses from “Not Otherwise Specified” diagnoses. These differences made it difficult to determine which studies could be compared, and how they should be compared to reveal “true” prevalence (Weissman, M., 1993), (Widiger, T., 1991) & (Lyons, M. & Jerskey, B., 2002). In this study, which appears to be the first of its kind, the prevalence of personality disorders in a rural, involuntarily committed, psychiatric population was examined as detailed in the following (Method) section.
The Hospital’s eight full-time staff psychiatrists routinely gave discharge diagnoses. Using the Hospital’s database, all discharges from the Hospital during a recent three-year period were analyzed. Initially, patients who had been discharged from the Hospital more than once during that period were included. Of the total number of discharges, a subset that included at least one personality disorder (PD) diagnosis was extracted, including PD NOS as an individual category. This subset was analyzed to find the frequency of each of the ten DSM-IV-TR personality disorder categories as well the Personality Disorder NOS category. Initially, the patients that were give multiple personality diagnoses were counted once in each of the appropriate PD categories. A second analysis was then carried out. It combined all patients with more than one personality diagnosis into one category. The above analyses were then repeated, excluding all but the final discharge diagnosis for each patient who was admitted/discharged more than once during the period under study. The frequency rate for each of the ten personality disorder categories, as well as Personality Disorder NOS, was explored, and correlated with hospital length of stay, and such demographic factors as age, educational level, gender and marital status. When appropriate, ANOVA was followed by Tukey Post-hoc testing, to delineate differences in population parameters. Gender differences were analyzed using the Chi-square test.
There were 2352 “discharge events” during the three-year period. Discharge events were defined as all discharges during the three years, which included multiple discharges for some individuals. Of the 2352 discharge events, 730 included at least one personality disorder (PD) diagnosis, including NOS. This represented 31% of the total number of discharge events, of which Borderline PD was most frequent (9.9%), followed by Antisocial (8.7%), and NOS (7.0%) (see Table 1). In the next step, the number of individuals discharged during the same period was found (1826), i.e., excluding all but the final discharge event for those who had multiple discharges. Of these 1826 individuals, 466 had been diagnosed with at least one personality disorder (see Table 1). In the final step, the fifty-five individuals who had more than one personality disorder diagnosis were extracted (see Table 1). Of these, 50 carried two diagnoses, and five carried three. By far, the most prevalent combination consisted of borderline and antisocial PD, followed by borderline and dependent.
The frequency and percentage of the ten DSM-IV-TR personality disorder categories and the percentages relative to one another.
Multiple Admissions Final Discharge Final Discharge
Multiple PD Counts Multiple PD Count Single PD Count
No PD Dx 1703 70.0 1703 72.4 1360 74.5
Borderline 235 9.9 32.2 184 6.2 24.2 113 6.2 24.2
Antisocial 204 8.7 27.9 160 7.2 28.1 131 7.2 28.1
NOS 165 7.0 22.6 166 6.6 26.0 121 6.6 26.0
Dependent 54 2.2 7.4 28 1.2 4.3 21 1.2 4.5
Narcissistic 20 .8 2.7 11 .5 1.7 8 .4 1.7
Paranoid 19 .8 2.6 9 .4 1.4 7 .4 1.5
Histrionic 11 .5 1.5 4 .2 .6 3 .2 .6
Schizoid 7 .3 1.0 3 .1 .5 2 .1 .4
Schizotypal 7 .3 1.0 5 .2 .8 3 .2 .6
Avoidant 7 .3 1.0 1 .0 .2 1 .1 .2
O-C 1 .0 .1 1 .0 .2 1 .1 .2
In this study, the typical profile of a patient with personality disorder was a never married, 34 year-old male, with an eleventh grade education, who had a median length of stay of 18 days. With respect to Borderline Personality Disorder, there were significantly more female patients than males (p < .000), while the opposite was true for males (p < .000).
It is believed that this is the first study of personality disorders in an involuntarily committed psychiatric population from the Appalachian Region of the United States. The population studied, 1826 individuals, represented 2352 separate discharge events, also making this one of the largest studies of personality disorders that has been conducted. Previous studies have pointed to an average prevalence of personality disorders of approximately 27% in clinical populations. The current study found, depending on the pattern used to count the data, rates of 25.5%, 27.6%, and 30%. Thus, it can be concluded that, with respect to the overall prevalence of personality disorders, the rural Appalachian population studied did not differ significantly from other populations so far studied.
Personality Disorder Categories
Of the ten PD categories, the prevalence of Antisocial PD has been the most thoroughly studied. In the 12 clinical samples reported by Widiger (1991) the rate ranged from 0.0% - 37% with a median prevalence of 7%. In the current study, a very similar rate (7.2%) was found, accounting for 28.1% of the PD subset.
Although borderline personality disorder is a relatively new diagnostic category, it is presently “the most common personality disorder seen in most psychiatric settings . . . and is overrepresented in clinical populations because of the tendency toward help-seeking” (Lyons & Jerskey, 2002). The rates as reported by Widiger (1991) varied from 11% to 70%, with a median rate of 31%. The current study found a prevalence rate of 6.2%, which accounted for 24.2% of the PD subset.
According to DSM-IV-TR, dependent personality is among the most frequently reported of the personality disorders encountered in mental health clinics (APA, 1994). Previous studies of clinical populations (Hirschfeld, 1991), (Widiger, 1991) & (Mors & Sorensen, 1994) revealed a range of 2%-55%, with a median of approximately 20%. In the current study, the prevalence rate of dependent personality disorder was found to be 1.2% of the total population, and 7.2% of the PD subset. As mentioned previously, the patient population in this study was involuntarily committed. A possible explanation for the low prevalence rate of Dependent PD at the Hospital is that the typical symptoms of Dependent PD are not of such a nature as would often warrant involuntary inpatient commitment.
In addition to an overview of the prevalence of PD in an inpatient clinical population in rural Appalachia, the current study also sought to point out the need for establishing a consistent approach for measurement and analysis. For example, as illustrated in Table 1, the prevalence of the total PD population varied depending on the method used. When patients with multiple PD diagnoses were counted two or three times, the finding suggested that 30% of the overall sample was PD. On the other end of the continuum, when only the last discharge was used and those with multiple diagnoses were put into a separate category, only 25.5% were defined as being PD.
Likewise, using different methodologies can yield different rankings for personality disorder categories. For example, when all discharge events were counted, Borderline PD was the most frequent, whereas counting only the final discharge resulted in Antisocial being more frequent. One way to explain this is that patients with Borderline PD had a greater frequency of re-admission than patients with Antisocial PD.
In this study, clinicians’ diagnoses were used to arrive at prevalence rates. Previous studies cited however, had used various instruments to reach their diagnoses. Despite this difference, this study’s findings were similar.
Limitations of this Study
The current study had the following limitations: 1) The population studied was comprised of individuals committed to the state psychiatric hospital. Given that the criteria for commitment in West Virginia are dangerousness to self and/or others, a selection bias could have been introduced into the results of the study i.e., patients presenting with symptoms not perceived as dangerous would be excluded. 2). Of all the ten PD categories, only Antisocial, Borderline & Dependent were discussed in some detail, because none of the other PD categories contained large enough samples to allow meaningful statistical analyses.
Suggestion for Future Research
A review of the published literature concerning the epidemiology of personality disorders revealed an important lack of methodological consistency. Some studies used number of individuals to calculate prevalence rates, while others relied on frequency of diagnoses, such that an individual with more than one PD diagnosis would have been counted multiple times. Such inconsistency is particularly problematic when considering the significant diagnostic overlap between categories. To make future studies more amenable to comparison, it is suggested that the data presented reflect both the frequency of each diagnostic category, as well as the number of PD diagnoses by each individual.
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