Volume 61, Issue 1, Pages 60-64 (January 2003)

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ABSTRACT

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Chronic prostatitis: symptom survey with follow-up clinical evaluation☆

Received 6 May 2002; accepted 22 August 2002.

Abstract

Objectives

To determine the prevalence of chronic prostatitis/chronic pelvic pain syndrome (National Institutes of Health Category III prostatitis) in Penang, Malaysia and estimate the proportion of cases ascertained by population survey that met consensus clinical criteria for “chronic prostatitis.”

Methods

One percent of 20 to 50-year-old men in Penang, Malaysia were surveyed using the National Institutes of Health Chronic Prostatitis Symptom Index. A clinical evaluation that included lower urinary tract localization studies was recommended for symptomatic subjects who met the survey definition to identify bacterial prostatitis and other diagnoses that would exclude them from the consensus clinical definition for chronic prostatitis (Category III).

Results

Of 3147 subjects surveyed, 275 (8.7%) met the survey criteria for chronic prostatitis. The prevalence of chronic prostatitis was 8.0% among Malays, 8.9% among non-Malays, and 16% among noncitizens (P = 0.025). The prevalence increased with age: 6.3% in 20 to 30-year-old men, 8.9% in 31 to 40-year-old men, and 12.6% in 41 to 50-year-old men (P <0.001). Of 87 subjects evaluated clinically, 65 (75%) met the consensus clinical criteria for chronic prostatitis.

Conclusions

Chronic prostatitis represents an important, international healthcare problem. A thorough clinical evaluation is necessary to verify that chronic prostatitis is indeed responsible for a patient’s pelvic pain and lower urinary tract symptoms.

Article Outline

• Abstract

• Material and methods

• Populations and recruitment strategy

• Sample size estimate

• Symptom survey definition of chronic prostatitis

• Clinical evaluation

• Clinical definition of chronic prostatitis

• Results

• Populations and recruitment

• Prevalence of chronic prostatitis by survey criteria

• Prevalence of chronic prostatitis by clinical evaluation

• Comment

• Conclusions

• Acknowledgment

• References

• Copyright

Limited data suggest that chronic prostatitis is a major healthcare issue.1 In the United States, prostatitis causes considerable economic loss and substantially reduces patients’ quality of life (QOL).2 Men with chronic prostatitis have a sickness impact profile similar to patients with unstable angina, recent myocardial infarction, or active Crohn’s disease.3 Unfortunately, little evidence-based information is available on the optimal approach to diagnosis and clinical management.4

It is difficult to determine whether these observations can be generalized to other geographic areas. The few published prevalence studies were based on a previous diagnosis by general practitioners or urologists, without specific clinical criteria for the diagnosis of prostatitis (Table I). 5, 6, 7, 8 Of these four studies, two were subject to possible recall bias because they relied on patients’ recollections of a clinical diagnosis.5, 8 Only three studies were based on symptom surveys using specific criteria for diagnosis (Table I).9, 10, 11 These studies used the National Institutes of Health Chronic Prostatitis Symptom Index (NIH-CPSI)12 for case definition. The NIH-CPSI was administered to the subjects, but these studies did not include follow-up clinical evaluations to verify that the cases ascertained by the symptom surveys met the established criteria for chronic prostatitis.13 The goals of this study were to determine the prevalence of chronic prostatitis in Penang, a cosmopolitan state in Northern Malaysia, and to estimate the proportion of cases ascertained by population survey that met the consensus clinical criteria for chronic prostatitis.

TABLE I.

Prevalence of prostatitis in population surveys


Investigator	Country, Male Population,Age (yr)	Methods, Definition of Prostatitis	Results (%)
Moon et al.,5 1997	U.S., 184 National Guard troops, 20–49	Nonvalidated survey: “history of prostatitis”	Prevalence: 5
Roberts et al.,7 1998	U.S., 2,115 randomly selected residents, 40–79	Nonvalidated survey: “Have you ever been told by a physician that you had recurrent prostatitis?”	Prevalence: 9
Collins et al.,6 1998	U.S., 58,955 randomly selected office-based physician visits, >18	National Ambulatory Medical Care Survey: diagnostic code of prostatitis	Urology visits: 8, primary care visits: 1
Mehik et al.,8 2000	Finland, 1,832 randomly selected residents, 20–59	Nonvalidated survey: previous diagnosis of prostatitis	“Life-time prevalence”: 14.2
Nickel et al.,9 2001	Canada, 868 patients of family practitioners, 20–74	NIH-CPSI: perineal/ejaculatory pain and score of ≥4 in pain domain	Prevalence: 9.7
Tan et al.,10 2001 (abstract)	Singapore, 845 men, 21–70	NIH-CPSI: pelvic pain/discomfort with urinary symptoms and impaired quality of life	Prevalence: 2.5
Roberts et al.,11 2001 (abstract)	U.S., 1,507 randomly selected residents, 40–79	NIH-CPSI: prostatitis-like symptoms	Prevalence of pain symptoms: 16, urinary symptoms: 35.7
Current study	Malaysia, 3,147 men, 20–50	NIH-CPSI: score of ≥1 on items 1 and 2, and symptoms for ≥3 months	Prevalence: 8.7

Key: NIH-CPSI = National Institutes of Health Chronic Prostatitis Symptom Index.

Material and methods

Populations and recruitment strategy

The NIH-CPSI12 was translated into two other major languages (Malay and Chinese) spoken by the population of Penang, with the accuracy of translations verified by back translation into English. The NIH-CPSI and its translations were found to be valid and reliable in the local population.14 The instruments were then administered to 20 to 50-year-old men recruited during Prostatitis Awareness Campaigns held at various sites in Penang, including hospitals, army camps, and the state university. The 20 to 50-year-old age group was chosen to minimize the potential symptom overlap with benign prostatic hyperplasia in older men. The campaign targeted a diverse sample of different racial/ethnic groups, cultures, and educational backgrounds. To improve the accuracy and validity of the results and to limit the possibility that literacy was a selection factor, trained medical personnel guided all subjects, regardless of educational level or literacy, in a standardized manner during the administration of the survey. The School of Pharmaceutical Sciences, University of Science Malaysia, Penang Hospital Committee on Clinical Studies approved the study.

Sample size estimate

Assuming a 10% prevalence of prostatitis (similar to studies from Europe and North America) and a 95% probability that the proportion obtained was ±1% of the population value, the sample size required was calculated to be approximately 3000 subjects.15

Symptom survey definition of chronic prostatitis

Subjects with a score of 1 or greater on NIH-CPSI items 1 and 2 (scoring range 0 to 6) and symptoms for at least 3 months were considered to meet the survey definition. These criteria were based on a new NIH consensus definition that recognizes urologic pain complaints as the primary component of this syndrome.

Clinical evaluation

Subjects who met the survey definition were invited to undergo clinical evaluation to identify diagnoses that would exclude them from the consensus definition, such as active urethritis, urogenital cancer, distal ureteral calculus, significant urethral stricture, or neurologic disease affecting the bladder.13 Laboratory evaluations included transabdominal ultrasonography of the urinary tract, urinalysis, and other clinically indicated studies, such as uroflowmetry for patients with suspected bladder outlet obstruction and intravenous urography for patients with suspected urolithiasis. Subjects also underwent lower urinary tract localization studies (“four-glass test”) with quantitative cultures and microscopy.

Clinical definition of chronic prostatitis

Symptomatic subjects who had none of the exclusion criteria and who did not have bacterial prostatitis met the clinical definition of chronic prostatitis.

Results

Populations and recruitment

The 3147 subjects surveyed represented approximately 0.3% of the 1.26 million residents of the state of Penang and approximately 1% of 20 to 50-year-old men. The racial and ethnic distribution was similar to the overall population (Table II, chi-square = 1.6, df = 2, P >0.25).16

TABLE II.

Racial/ethnic distribution of Penang’s population and sample surveyed


Group	Non-Malay (%)	Malay (%)	Noncitizens (%)
Overall population14 (n = 1.26 million)	56.8	40.1	3.1
Sample surveyed* (n = 3147)	57.9	39.1	3.0
Chronic prostatitis† (n = 275)	8.9	8.0	16.1

Comparison of overall population to sample surveyed (chi-square = 1.6, df = 2, P >0.25).

†

Comparison of proportion with prostatitis in each group to sample surveyed (chi-square = 23.2, df = 2, P <0.001).

Prevalence of chronic prostatitis by survey criteria

Of 3147 subjects, 275 (8.7%) met the survey definition for chronic prostatitis (95% confidence interval 7.7% to 9.7%). The median age of the subjects with chronic prostatitis was 35 years compared with 33 years for subjects without prostatitis (Mann-Whitney U = 322,053; P <0.001).

The prevalence of chronic prostatitis by the survey criteria was 8.0% among Malays (number surveyed 1231), 8.9% among non-Malays (ethnic Chinese and Indians, number surveyed 1823), and 16% among noncitizens (number surveyed 93; chi-square = 7.4, df = 2, P = 0.025). The prevalence of chronic prostatitis was 6.3% in 20 to 30-year-old men (number surveyed 1250), 8.9% in 31 to 40-year-old men (number surveyed 1152), and 12.6% in 41 to 50-year-old men (number surveyed 745; chi-square = 23.2, df = 2, P <0.001).

Prevalence of chronic prostatitis by clinical evaluation

Of the 275 subjects with chronic prostatitis as ascertained by the survey criteria, 87 (32%) were evaluated clinically. The subjects evaluated clinically had a median value of 9, 4, 7, and 19 for pain, urinary, QOL impact, and NIH-CPSI total score, respectively, that was significantly higher than the corresponding score of the symptomatic subjects who did not undergo follow-up clinical evaluation (median score of 7, 2, 6, and 16, respectively, with P <0.02 for each scale). The reasons why symptomatic subjects were not evaluated included “not reachable” (65%), “did not have time” (18%), “symptoms resolved” (13%), “symptoms were mild” (2%), “fear of medical checkup” (1%), and “sought medical care elsewhere” (1%).

Of the 87 clinically evaluated subjects, 65 (75%) met the consensus criteria. The 22 remaining symptomatic subjects had other diagnoses, including symptomatic varicocele (n = 7), musculoskeletal pain in anatomic areas other than the pelvis (n = 7), lower urinary tract calculi (n = 4), epididymitis (n = 2), and symptomatic inguinal hernia (n = 2). The 22 subjects with other diagnoses had a median pain score of 7 and a median QOL impact score of 6, comparable to the scores for subjects who met the clinical criteria (median pain score 9, QOL impact score 7; P >0.07). However, subjects with chronic prostatitis had a median urinary score of 4 and median total NIH-CPSI score of 19, higher than the scores of subjects with other diagnoses (median urinary score 2, total score 16; P <0.03).

Comment

We studied an ethnically and racially diverse Asian population. The 8.7% prevalence of chronic prostatitis among men in Northern Malaysia was comparable to the 2% to 10% rates reported in most surveys, although the definitions varied among the studies. For example, a recent study by Nickel et al.9 defined “prostatitis-like symptoms” as the presence of pain in the perineum and/or during ejaculation and a score of 4 or greater in the NIH-CPSI pain domain. Using this definition, the prevalence of chronic prostatitis in our population was 2.6%, higher than the rate reported by Nickel et al. (9.7%). We found a higher prevalence rate than reported in neighboring Singapore (2.5%). This discrepancy was likely because the case definition used in the Singapore survey included the presence of pain, urinary symptoms, and impaired QOL, and our study used the presence of pain symptoms for at least the past 3 months.1

These findings provide critical support for the growing data suggesting that chronic prostatitis represents an important, international healthcare problem. Unfortunately, treatment is unsatisfactory for the great majority of patients. Because no evidence-based guidelines are available,4 there is a substantial need to define the causes, consequences, and optimal management.

We translated the NIH-CPSI into two other languages commonly spoken in Northern Malaysia, and trained medical translators to guide subjects in answering the survey questions. The lowest rate (8%) was among Malay men compared with 9% among non-Malays and 16% among noncitizens (P = 0.025). Noncitizens were mainly foreign, unskilled workers who had less education and were of lower economic status. Although such differences may reflect ascertainment or cultural bias, genetic, dietary, or behavioral factors may also prove important. Confirmation of different rates among different racial/ethnic groups may provide critical insights into the causes of chronic prostatitis.

The finding that chronic prostatitis was most prevalent in older men is consistent with previous studies. Collins et al.6 reported that prostatitis was diagnosed more commonly in 36 to 65-year-old men than in 18 to 35-year-old men. Mehik et al.8 reported that prostatitis was more common among 50 to 59-year-old men than among younger men.

The present study was unique among population-based symptom surveys in that we recommended clinical evaluation to all those identified in the survey study as having chronic prostatitis to verify that it was indeed responsible for their symptoms. Of 275 subjects with chronic prostatitis by the survey criteria, 87 (32%) agreed to an uncomfortable clinical evaluation. This evaluation required at least one additional clinic appointment. On the basis of the NIH-CPSI scores, subjects who were clinically evaluated had more severe symptoms. However, we found no statistically significant difference in the NIH-CPSI pain scores of subjects who met the clinical definition of chronic prostatitis and those who had other clinical conditions. Of the 87 subjects evaluated, 65 (75%) met the clinical criteria for chronic prostatitis. Thus, it is unlikely that symptom surveys alone will prove adequate for diagnosis. This finding provides the first population-based data supporting the consensus recommendation for clinical evaluation to verify the diagnosis of chronic prostatitis.13

A total of 25% of patients who met the survey criteria for chronic prostatitis had other diagnoses that were responsible for their symptoms. The prevalence of other diagnoses is likely to be different in other geographic areas. For example, we excluded 4 (18%) of 22 cases because of symptomatic lower urinary tract calculi. Such stones are common in Malaysia, which is located in the geographic “stone belt.” Hence, the 25% prevalence of other diagnosis should be verified in other populations.

The present study provides external validation for the NIH-CPSI. Our population was diverse, with different races, languages, and cultures, and included subjects who were economically disadvantaged and illiterate. Our data also emphasize that survey studies using the NIH-CPSI are likely to provide substantial overestimates of the true clinical prevalence of chronic prostatitis. This can be expected, because the NIH-CPSI was evaluated for its reliability and validity as an outcome measure, not as a diagnostic tool.12

This study has limitations. We surveyed almost 1% of adult men in Penang. The racial/ethnic composition was similar to the overall population. However, we do not know that the selection procedures ensured that the sample represented our overall population in all relevant variables. Hence, the group was not necessarily reflective of the true population. To limit the chance that literacy or linguistic issues could influence our findings, trained medical translators were available to guide the subjects. Perhaps these procedures introduced an ascertainment bias. In addition, the use of trained medical personnel to administer the NIH-CPSI might have introduced a bias, because the NIH-CPSI was validated as a self-administered questionnaire. We evaluated almost one third of patients clinically, but it is possible that these subjects were different from the overall population. We also could not classify the 65 subjects who met the clinical criteria for chronic prostatitis into Category IIIa and IIIb prostatitis, because we did not get a semen analysis on every patient. Because of cultural and religious prohibitions, especially among the Malays, very few subjects agreed to provide semen samples.

Conclusions

The prevalence of chronic prostatitis was 8.7% by the survey criteria in our diverse population. Malays had significantly lower rates of chronic prostatitis than did non-Malays or noncitizens. A thorough clinical evaluation confirmed that 75% of subjects who met the survey criteria also met the clinical criteria for chronic prostatitis. These findings suggest that chronic prostatitis represents an important international health problem and support the need to define the causes, consequences, and optimal management.

Acknowledgements

To Drs. Chong Siang Tan, Chek Lang Ding, Chit Sin Loh, Johari Jantan, Khairuddin Husain, and Professor Soon Hoe Quah for their valuable support, advice, and clinical assistance; and to the Division of Health Services, Ministry of Defense Malaysia, the Department of Nursing, and the College of Nursing of Lam Wah Ee Hospital Penang for providing valuable assistance in the survey.

References

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2. 2 Calhoun EA, Collins MM, O’Leary MP, et al. What is the economic impact of chronic prostatitis?. (abstract) J Urol. 2001;165(suppl):26.

3. 3 Wenninger K, Heiman JR, Rothman I, et al. Sickness impact of chronic nonbacterial prostatitis and its correlates. J Urol. 1996;155:965–967. Abstract | Full Text | Full-Text PDF (492 KB) | CrossRef

4. 4 Collins MM, MacDonald MS, Wilt TJ. Diagnosis and treatment of chronic abacterial prostatitis (a systematic review). Ann Intern Med. 2000;133:367–381. MEDLINE

5. 5 Moon TD, Hagen L, Heisey DM. Urinary symptomatology in younger men. Urology. 1997;50:700–703. Abstract | Full-Text PDF (400 KB) | CrossRef

6. 6 Collins MM, Stafford RS, O’Leary MP, et al. How common is prostatitis? A national survey of physician visits. J Urol. 1998;159:1224–1228. Abstract | Full Text | Full-Text PDF (616 KB) | CrossRef

7. 7 Roberts RO, Lieber MM, Rhodes T, et al. Prevalence of a physician-assigned diagnosis of prostatitis (the Olmstead County Study of Urinary Symptoms and Health Status among men). Urology. 1998;51:578–584. Abstract | Full Text | Full-Text PDF (189 KB) | CrossRef

8. 8 Mehik A, Hellstorm P, Lukkarinen O, et al. Epidemiology of prostatitis in Finnish men (a population-based cross-sectional study). BJU Int. 2000;86:443–448. MEDLINE | CrossRef

9. 9 Nickel JC, Downey J, Hunter D, et al. Prevalence of prostatitis-like symptoms in a population-based study using the National Institutes of Health Chronic Prostatitis Symptom Index. J Urol. 2001;165:842–845. Abstract | Full Text | Full-Text PDF (72 KB) | CrossRef

10. 10 Tan JK, Png DJ, Liew LC, et al. Prevalence of prostatitis-like symptoms (PS) in a population based study. (abstract) J Urol. 2001;165(suppl):23. Abstract | Full Text | Full-Text PDF (430 KB) | CrossRef

11. 11 Roberts RO, Jacobson DJ, Lieber MM, et al. Prevalence of prostatitis-like symptoms in community-dwelling men. (abstract) J Urol. 2001;165(suppl):24.

12. 12 Litwin MS, McNaughton-Collins M, Fowler FJ, et al. The National Institutes of Health Chronic Prostatitis Symptom Index (development and validation of a new outcome measure). J Urol. 1999;162:369–375. Abstract | Full Text | Full-Text PDF (790 KB) | CrossRef

13. 13 Krieger JN, Nyberg JR, Nickel JC, et al. NIH Consensus Definition and Classification of Prostatitis. JAMA. 1999;282:236–237. MEDLINE | CrossRef

14. 14 Cheah PY, Yuen KH, Liong ML, et al: Reliability and validity of the National Institutes of Health Chronic Prostatitis Symptom Index (NIH-CPSI) in a Malaysian population. Int J Urol 9(suppl): A55, 2002

15. 15 Sheffler WC: Proportions and chi square, in Statistics for Health Professionals. Buffalo, Addison-Wesley Publishing, 1984, pp 224–225

16. 16 Shaari AR: Population, in State/District Data Bank Malaysia 2000. Kuala Lumpur, Department of Statistics Malaysia, 2001, pp 56–60

a University of Science Malaysia School of Pharmaceutical Sciences, Penang, Malaysia

b Department of Urology, Lam Wah Ee Hospital, Penang, Malaysia

c Department of Urology, Penang Adventist Hospital, Penang, Malaysia

d Department of Urology, Gleneagles Medical Centre, Penang, Malaysia

e Department of Urology, Penang Hospital, Penang, Malaysia

f Department of Urology, Island Hospital Penang, Penang, Malaysia

g Department of Urological Surgery, University of Washington School of Medicine, Seattle, Washington, USA

Reprint requests: John N. Krieger, M.D., Department of Urology, University of Washington School of Medicine, 1660 South Columbian Way, Seattle, WA 98108, USA

☆ This study was supported in part by an unrestricted grant from Abbott Laboratories, Malaysia, and the U.S. National Institutes of Health, Bethesda, Maryland.

PII: S0090-4295(02)02081-2

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