OAB and interstitial cystitis/bladder pain syndrome show considerable overlap

There is considerable overlap between symptoms in patients with interstitial cystitis/bladder pain syndrome (IC/BPS) and those with overactive bladder (OA), US researchers have shown.

The findings raise the possibility that the two conditions represent a continuum of a bladder hypersensitivity syndrome, say H Henry Lai (Washington University School of Medicine, St Louis, Missouri) and study co-authors writing in the Journal of Urology.

The researchers studied three groups of patients: 26 with a diagnosis of IC/BPS, 53 with OAB and 30 healthy controls. All participants were assessed with validated questionnaires addressing four key aspects of their symptoms: pain, frequency, urgency and incontinence.

Lai’s team found that the prevalence of different symptoms varied among the groups. For instance, severe pain symptoms were significantly more prevalent among patients with IC/BPS than in those with OAB, and least prevalent in healthy controls.

Meanwhile, incontinence symptoms were significantly more prevalent in patients with OAB than in those with IC/BPS and least prevalent in healthy controls.

The severity of both frequency and urgency symptoms was similar between patients with IC/BPS and those with OAB, and in both instances higher than in controls.

Further analysis revealed substantial overlap of symptoms between the patient groups. One-third of OAB patients reported pain or discomfort when the bladder fills – a hallmark feature of IC/BPS, according to the researchers. One-quarter of OAB patients reported pain or burning during urination and 28% reported pain in the suprapubic and bladder area.

Among IC/BPS patients, more than two-thirds reported some incontinence in the past 4 weeks; 46% had urgency incontinence and 42% had stress incontinence.

The authors found that there was a significant positive linear correlation between bladder pain (rated on a numeric rating scale) and urinary incontinence (assessed using the International Consultation on Incontinence Questionnaire–Urinary Incontinence), and that responses on these two measures distinguished between OAB and IC/BPS with a sensitivity of 90.6% and a specificity of 96.1%.

They conclude that there is considerable overlap between the two diagnoses and that OAB and IC/BPS may be different stages on a clinical continuum of bladder hypersensitivity.

“Ultimately we need comparative mechanistic studies of IC/BPS and OAB to understand how the two syndromes are similar and different”, they write. “Results from the current study called for a re-thinking of the relationship between symptom clusters and presumptive clinical diagnoses.”