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Urologic Diseases Research Updates
Summer 2010

Evidence Found for Overlap between Urological and Nonurological Unexplained Clinical Conditions

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Researchers at the National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK) have found substantial overlap between urological and nonurological unexplained clinical conditions characterized by pain.

An article published in the November 2009 issue of the Journal of Urology focuses on the overlap of urological conditions such as chronic pelvic pain (CPP), interstitial cystitis (IC), painful bladder syndrome (PBS), chronic prostatitis/chronic pelvic pain syndrome (CP/CPPS), and vulvodynia with nonurological conditions including fibromyalgia (FM), chronic fatigue syndrome (CFS), temporomandibular joint and muscle disorders (TMD), and irritable bowel syndrome (IBS). The research was funded by the NIDDK.

Maria Angeles Bullones Rodriguez, Department of Psychology, University Rey Juan Carlos, Madrid, Spain, and colleagues searched 12 databases using hallmark symptoms and syndromes as search terms. They identified and reviewed 1,037 full-length published articles in eight different languages that were published between 1966 and 2008. The articles included in this review examined the comorbidity or overlap of at least one urological condition or hallmark symptom with at least one nonurological condition or hallmark symptom.

“The literature suggests considerable comorbidity between urological and nonurological unexplained clinical conditions. The most evidence for overlap, up to 79 percent, was between IBS and urological unexplained clinical conditions, particularly CPP,” wrote Rodriguez and colleagues.

“This overlap may reflect publication bias or the anatomical fact that urological CPP conditions and IBS develop in a similar region of the body and involve visceral pain sensations,” Rodriguez and colleagues stated in the journal publication. However, the findings generally support assertions of overlap among some or all of the urological and nonurological unexplained clinical conditions, the researchers added.

The few studies of FM, CFS, and TMD suggest a more modest comorbidity with urological unexplained clinical conditions. The article states that some experts argue the comorbidity of FM, CFS, TMD, and IBS could result from similarities in their case definitions. However, the researchers presented another viewpoint: “Although this explanation may apply to the overlap between urological pelvic pain conditions and IBS, urinary and pelvic pain symptoms are not part of the symptom criteria for FM, CFS, or TMD. Thus, commonalities in symptom criteria cannot completely account for the overlap we summarize.”

Concerning unexplained clinical conditions, the article states that despite decades of research, their etiology and pathophysiology remain elusive. The researchers identified three dominant perspectives on the mechanisms of these conditions. First, they cited physiological processes, including neuroendocrine, immunological, and neurotransmitter dysfunction in the central nervous system. Second, they cited victimization, abuse, and trauma. Third, they listed psychological distress, psychological disorders, stress tolerance, and stress recovery. In some cases, affected patients did not have symptoms from any of the three dominant perspectives. Therefore, a multidimensional conceptual model seems better suited to guide research and understanding of these conditions and co-occurrence.

The authors argued that a more broadly based conceptual model can better investigate etiology, clinical manifestations, comorbidity, and prognosis. Examining pain, which is prominent across the syndromes of interest, is crucial to understanding their substantial comorbidity.

The researchers stated that although comorbidity was shown, earlier studies have several methodological shortcomings that undermine the strength of the conclusion and limit comparability across studies. The researchers also asserted that future studies should adhere to the established research diagnostic criteria for each condition, and longitudinal cohort designs are needed to examine risk factors, temporal onset, and prognosis. These well-controlled studies will advance the understanding of and improve treatment for these conditions.

More information about research projects funded by the National Institutes of Health can be found by using the Research Portfolio Online Reporting Tools (RePORT) Expenditures and Results (RePORTER) tool located at The research described in this article is funded under NIDDK grant number 3U01DK082325–02S1.

The National Kidney and Urologic Diseases Information Clearinghouse, an information dissemination service of the NIDDK, has fact sheets and easy-to-read booklets about CPP, IC, PBS, and CP/CPPS. For more information and to obtain copies, visit

NIH Publication No. 10-5743
August 2010

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