To the Editor: Roger K. Blashfield, Ph.D., and Vincent Intoccia, B.A. (1), after a search of MEDLINE, 1966–1995, reported that the growth rate in the literature on personality disorders has not increased since the introduction of DSM-III. There are problems involved in the methodology chosen. The leading journals in the field, Personality and Individual Differences, official journal of the International Society for the Study of Individual Differences (founded in 1983), and the Journal of Personality Disorders, official journal of the International Society for the Study of Personality Disorders (founded in 1988), are indexed in a variety of databases but not in MEDLINE. Thus, MEDLINE seems to be an insufficient source from which to elucidate the growth of literature in the field. Furthermore, the MeSH heading "personality disorder" in MEDLINE is not used to cover personality disorders as they are usually defined in the literature. Furthermore, the MeSH headings of individual personality disorders have been imprecise and have changed during the years. Dr. Blashfield and Mr. Intoccia (1) had to search for individual personality disorders and total them. However, it has been more common to use broad personality questionnaires to cover all personality disorders, and often individual personality disorders are not reported in the title or as key words.

Thus, we have made a reevaluation through a search of PsycINFO, in which both of the previously mentioned journals are indexed. The search was performed on "personality disorders," both as a key word and as title text.

In 1980 and after, the number of publications concerning personality disorders increased rapidly. The best-fitting trend line is an exponential curve. Before 1980 (1968–1979), the mean number of publications per year was 39.3 (SD=16.4), and in 1980 and after, it increased to 241.5 (SD=142.8) articles a year (z=4.06, p<0.0001, Mann-Whitney U test). We searched the 5 years immediately before the introduction of DSM-III (1975–1979) and the last 5 years (1991–1995), and we found that the number of publications increased from 50.2 (SD=6.0) to 403.2 (SD=36.5) articles a year (z=2.61, p<0.01, Mann-Whitney U test). The rate of increase is more pronounced than the growth of the general medical literature, which doubles about once every 23 years (1).

In a recent article (2), McDonald et al. demonstrated that out of the 977 psychiatry journals identified in Ulrich’s International Periodicals Directory, 38% were indexed in PsychLIT, 34% in EMBASE, 25% in BIOSIS, and only 24% in MEDLINE. However, a total of 213 abstracting and indexing services were identified. Thus, it is easy to agree with McDonald et al. (2) that it is important to search more than one or even two databases to ensure optimal coverage of the literature.