ReviewEpidemiology of prostatitis
Introduction
A resurgence of interest in prostatitis has occurred during the last decade. This has been accompanied by a new level of understanding of the epidemiology, morbidity and economic impact of these conditions. Much progress dates from the recognition that infection and inflammation are important in certain prostatitis syndromes. Despite limited information on the causes of other prostatitis syndromes, these conditions can be defined and important treatment studies have been initiated. This article employs evidence-based methods to review the epidemiology of prostatitis syndromes, examines the clinical implications of these data, and outlines areas for future research.
Prostatitis describes a combination of infectious diseases (acute and chronic bacterial prostatitis), a chronic pelvic pain syndrome and asymptomatic inflammation. The National Institutes of Health classification has been accepted internationally and includes four syndromes (Table 1) [1].
Category I, acute bacterial prostatitis, is characterised by an acute bacterial urinary tract infection.
Category II, chronic bacterial prostatitis, is a persistent bacterial infection of the prostate leading to recurrent urinary tract infections caused by the same bacterial strain.
Category III, chronic prostatitis/chronic pelvic pain syndrome, is characterised by chronic pelvic pain symptoms in the absence of urinary tract infection. The symptoms include characteristic urogenital pains, voiding and sexual dysfunction that substantially reduce patients’ quality of life. There are two subtypes.
- a.
Inflammatory chronic prostatitis/chronic pelvic pain syndrome is associated with leukocytes in the expressed prostatic fluid, post-prostate massage urine or seminal fluid.
- b.
Non-inflammatory chronic prostatitis/chronic pelvic pain syndrome with no evidence of urogenital inflammation.
Category IV, asymptomatic inflammatory prostatitis, occurs in patients who have no symptoms but who have documented inflammation in prostatic tissue or in their seminal fluid. For example, the most common prostatic inflammation (‘prostatitis’ as diagnosed by pathologists) represents the most common benign condition found in men who have biopsies to evaluate possible prostate cancer.
Papers published in peer-reviewed journals were included in this review. Papers in non-peer-reviewed supplements were excluded. An exhaustive list was obtained through the major databases (e.g., Medline, Embase, Cochrane Library and Science Citation Index). Search terms included: prostatitis, pelvic pain, inflammation, epidemiology and survey. We also reviewed tables of contents of the major urology journals and other relevant journals, for the previous 3 months, to take into account possible delay in indexing papers in the databases. These approaches identified more than 4000 references. After reviewing the titles and abstracts, 86 articles were identified for detailed review.
For inclusion in this analysis, studies were required to meet criteria that have been outlined for epidemiological studies of prostatitis (Table 2) [2]. Three criteria were required: (1) Included studies were population-based rather than case series or referral patients from tertiary care institutions. (2) A clear case and standardised definition was required, ideally a reasonable relationship to patients seen in routine clinical practice. (3) Publication in the peer-reviewed literature was required.
In addition to the required criteria, at least one other desirable criterion was necessary for inclusion. (4) It is desirable to incorporate a validated survey instrument such as the National Institutes of Health Chronic Prostatitis Symptom Index (NIH-CPSI) [3]. To facilitate evaluation of varied populations, the NIH-CPSI has been translated and validated for use in English [3], Spanish [4], Japanese [5], Chinese [6], Malay [6], German [7], Korean [8], Finnish [9], Italian [10], French [11] and Estonian [12]. However, a population-based study found low agreement between physician-diagnosed prostatitis and the NIH-CPSI pain measures, suggesting that the index, by itself, may have limited ability to determine the presence or absence of prostatitis [13]. Therefore, use of the NIH-CPSI was considered desirable, but was not required for inclusion. (5) A standardized strategy for surveying the population should be used to assure that participants are likely to represent the overall population. The optimal strategy should incorporate a mechanism to verify that cases identified in the survey actually met the case definition, such as a detailed chart review or, ideally, a standardized clinical examination. (6) The population should be large enough to provide reasonable statistical power for the desired comparisons.
Section snippets
Limitations of the available literature
Although the studies described below met the inclusion criteria, most had important limitations. Few studies included adequate microbiological evaluation. Most did not include chart reviews or physical examination to assure that subjects did not have the exclusion criteria for chronic prostatitis (listed in Table 1, footnote b). Most studies relied exclusively on symptom questionnaires, or portions of validated symptom assessment instruments. Such surveys are easy to administer, but they were
Natural history of prostatitis symptoms
We identified only two studies that considered the natural history of prostatitis symptoms that met the inclusion criteria [26], [27]. Both studies considered the outcome after the usual clinical treatment in North American populations.
Nickel and associates conducted a 1-year follow-up study of their cohort from Eastern Canada [26]. A questionnaire incorporating the NIH-CPSI pain and voiding domains was compared for 40 men who had reported prostatitis-like symptoms in their initial survey and
Discussion
The limited number of studies that met our evidence-based criteria were sufficient to support the conclusion that prostatitis is an important worldwide problem that merits additional investigation. The prevalence of prostatitis-like symptoms (defined variously) ranged from 2% to 9.7%, with a mean prevalence of 8.2%. Possible reasons for this almost five-fold variation in prevalence include differences: in study design, selection of populations for investigation, cultural factors, variations in
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