Prostatitis is an enigmatic condition that affects men at all points of their lives, a fact that nobody can overlook. It also has an impact on their health in general and it forms the third part of the prostate pathology alongside prostate cancer and benign prostate hyperplasia (Keltikangas-Järvinen et al. 1989, de la Rosette et al. 1993b, Berghuis et al. 1996, Wenninger et al. 1996, Roberts et al. 1997).
Prostate cancer and benign prostatic hyperplasia are two important reasons for increased healthcare costs, especially due to the need for hospitalization, and not far away is the growing group of prostatitis patients who are increasingly seeking help from modern medicine on an outpatient basis (McNaughton-Collins et al. 1998b, Roberts et al. 1998, McNaughton-Collins et al. 1999). There are some epidemiological studies showing that this condition is very common and that there are factors related to age, education, economic and marital status, recreational activities, sexual behaviour, infections of the urinary tract, concomitant diseases reflecting autoimmunity, psycho-mental disturbances etc., which may provide clues to a better understanding of its aetiology (Krieger et al. 1993a, Alexander & Trissel 1996, Moon 1997, McNaughton-Collins et al. 1998a, McNaughton-Collins et al. 1998b, Roberts et al. 1998, Nickel et al. 2001).
Epidemiology differs from clinical medicine in that the unit of intrest is the population rather than the individual. It may be defined as the study of the distribution, frequency and determinants of health problems and disease in human populations, allowing the distribution of health and illness to be described in a population, mostly by measuring the occurrence of illness. It also provides tools for comparing populations in terms of their health characteristics. Measures of disease frequency are of two basic types: incidence and prevalence (Rothman 1986).
Incidence focuses on events of a disease and represents an attempt at measuring the frequency of disease occurrence in a given population. There are several possible measures of incidence, taking account of the time elapsing before occurrence of the disease, and/or number of individuals in the population who become ill. These include the incidence proportion (or incidence at risk), cumulative incidence and incidence density (also known as incidence rate or force of morbidity) (Rothman 1986).
Prevalence focuses on disease status, and may be defined as the proportion of the population affected by disease at a given point in time, sometimes referred to as the term point prevalence (Rothman 1986).
The prevalence of prostatitis refers to the proportion of men who suffer and/or have suffered from it at a specific point in time (point prevalence) (McNaughton-Collins et al. 1998b, Roberts et al. 1998, Nickel et al. 2001) or at defined period of time (period prevalence). Its incidence is the frequency of occurrence of new cases derived from the monitoring of subjects over time. The incidence data are usually obtained from retrospective and prospective cohort studies and prevalence data from cross-sectional asessments (Drabick et al. 1997, Moon et al. 1997, Roberts et al. 1998, McNaughton-Collins & Barry 1999, Nickel et al. 2001). The prevalence can be also defined from an autopsy series (Mehlhorn 1987).
The majority of studies on prostatitis are nevertheless clinical series, and their results have provided useful information and increased our clinical knowledge about to the disease and its aetiological agents (Poletti et al. 1985, Doble et al. 1989b, Weidner et al. 1991b, Shortliffe et al. 1992, Nickel & Costerton 1993, Berger et al. 1997).
Clinical studies are essential for the evaluation of potential treatment strategies (Schaeffer & Darras 1990, Krieger & Egan 1991, Weidner et al. 1991b, Nickel & Sorensen 1996), and it is these that have formed the basis for the new NIH classification of prostatitis (Moon et al. 1997, Krieger et al. 1999, Litwin et al. 1999).
Clinical studies have provided a valid characterization of the signs and symptoms of prostatitis (Krieger & Egan 1991, de la Rosette et al. 1993a, Egan & Krieger 1994, Krieger et al. 1996a, Egan & Krieger 1997) and future guidelines for using specific laboratory investigations, e.g. EPS (Anderson & Weller 1979, Schaeffer et al. 1981) and ultrasonography to judge the clinical relevance of findings in patients (Doble et al. 1989a, de la Rosette et al. 1995).
Several population-based cross-sectional surveys and series of clinical data from outpatient visits have shown that the prevalence of prostatitis symptoms is up to 25% (Moon 1997, Roberts et al. 1997, Pavone et al. 2000), whereas the prevalence based only on questionnaires and physicians’ diagnoses is reported to be between 4% and 11% (Moon et al. 1997, McNaughton-Collins et al. 1998b, Roberts et al. 1998, Nickel et al. 2001) and that based on autopsy material ranges from 61% (Mehlhorn 1987) up to the 98% obtained using histopathological data from TURP chips (Kohnen & Drach 1979).
Case-control studies represent another design frequently used to collect comprehensive data related to prostatitis symptoms (Berger et al. 1989, Weidner et al. 1991a, Weidner et al. 1991b, Berger et al. 1997). This means, that the information provided is closely dependent on a very locally available ”super”-selected population (a certain hospital, a certain urological clinic or a certain area in a specific country) and illuminates a very narrow part of the whole problem. The data are hard to compare and to interpret and are apt to lead to overestimation or underestimation of the real situation. All the time that the definition of prostatitis is not the same for all, our understanding of the epidemiology of prostatitis will be limited and scarce (Nickel et al. 2001).
Following the work of the American Urological Association (AUA) to define the symptoms associated with benign prostatic hyperplasia (BPH), several investigators have developed their own questionnaires (Brähler & Weidner 1986, Neal & Moon 1994, Alexander & Trissel 1996, Krieger et al. 1996b, Nickel & Sorensen 1996).
The importance of using standardized questionnaires for the evaluation of prostatitis patients is that it allows the work of different authors to be compared. And still more important is the use of standardized diagnostic criteria. This work was started under the guidance of J.C. Nickel and the International Prostatitis Collaborative Network, and was published for clinical use by Litwin et al. (1999).
Concerning the use of specific questionnaires to study unselected populations of men in order to collect epidemiological data, the situation among the prostatitis researchers is not very encouraging. So far only one large survey (54 questions), based on use of the Internet (Alexander & Trissel 1996), the population-based study by Roberts et al. (1998) (134 questions) and a few others with up to 58 questions (Moon et al. 1997) have been directed at prostatitis patients or their physicians/urologists (de la Rosette et al. 1992a, Neal & Moon 1994, Wenninger et al. 1996, Moon 1997, Nickel et al. 1998).
The first investigation into practical patterns/messages related to prostatitis was published by de la Rosette et al. (1992a), containing information on prostatitis among patients seen by primary care physicians and urologists. This pointed to three main discrepancies: that physicians see older patients than urologists, that physicians see only a tenth of the number of patients that urologists do, and that physicians mainly think that the aetiology of prostatitis is infectious, whereas urologists consider non-infectious causes the most important. At least half of the physicians and urologists think that it is very important to take note of the psychic component of chronic prostatitis. Half of the urologists perform EPS and a semen culture for diagnostic purposes, and treatment consists of one or more courses of antibiotics, analgesics and some supportive advice (de la Rosette et al. 1992a).
When we compare these results with the surveys published by Moon (1997) and Nickel et al. (1998), many similarities emerge with regard to the opinions of physicians and urologists. These surveys show quite remarkable consistency from country to country, but the differences in the numbers of patients seen by doctors mainly represent differences between health care services rather between rates of diagnosis. These surveys (de la Rosette et al. 1992a, Moon 1997, Moon et al. 1997, Nickel et al. 1998) show that the use of antibiotics without any reason or any evidence of bacteria in the prostatic fluid and/or urine is the norm rather than the exception. It represents largely accepted behaviour and is supported by the results of Lowentritt et al. (1995) and Berger et al. (1997) concerning ”cryptic infections” of the prostate gland.
The textbooks of urology presume that acute and chronic bacterial prostatitis are easily defined, diagnosed and treated (Meares 1998). Fortunately, even when no prostatic fluid culture is performed, the use of one or more courses of antibiotics will generally elicit a therapeutic response. Category III patients are a problem to diagnose and treat, as inflammation may or may not be present (Krieger et al. 2000a). Additionally, when about 90% of bacterial cultures are negative, this causes a normalizing tendency, or clinical behaviour designed to avoid proper laboratory diagnostics in clinical practice, leading to an erroneous basis for reaching treatment decisions. The textbooks (Meares 1998) also suggest a possible infectious aetiology of prostatitis even when conventional cultures are negative (Lowentritt et al. 1995, Berger et al. 1997, Kieger et al. 2000b) and Krieger et al. (2000c) have found some signs of bacterial presence in prostate tissue in a case of prostatitis using a polymerase chain reaction (PCR) technique, but the clinical significance of this is still unresolved .