Diagnostic accuracy study of anorectal manometry for diagnosis of dyssynergic defecation

Abstract

Objective The diagnostic accuracy of anorectal manometry (AM), which is necessary to diagnose functional defaecatory disorders (FDD), is unknown. Using blinded analysis and standardised reporting of diagnostic accuracy (STARD), we evaluated whether AM could discriminate between asymptomatic controls and patients with functional constipation (FC). Design Derived line-plots of anorectal pressure profiles during simulated defaecation were independently analysed in random order by 3 expert observers blinded to health status in 85 women with FC and 85 age-matched asymptomatic healthy volunteers (HV). Using accepted criteria, these pressure profiles were characterized as normal (i.e. increased rectal pressure coordinated with anal relaxation) or types I-IV dyssynergia. Inter-observer agreement and diagnostic accuracy were determined. Results Blinded consensus-based assessment disclosed a normal pattern in 16/170 (9%) of all participants and only 11/85 (13%) HV. The combined frequency of dyssynergic patterns (I-IV) was very similar in FC (80/85 [94%]) and HV (74/85 [87%]). Type I dyssynergia (‘paradoxical’ contraction) was less prevalent in FC (17/85 [20%] than HV (31/85 [36.5%], p=0.03). After statistical correction, only type IV dyssynergia was moderately useful for discriminating between FC (39/85 [46%] and HV 17/85 [20%], p=0.001, PPV=70.0%, positive LR=2.3). Inter-observer agreement was substantial or moderate for identifying a normal pattern, dyssynergia types I and IV, and FDD, and fair for types II and III. Conclusions While the interpretation of AM patterns is reproducible, nearly 90% of HV have a pattern that is currently regarded as “abnormal” by AM. Hence AM is of limited utility for distinguishing between FC and HV.

How to Perform and Interpret a High-resolution Anorectal Manometry Test

“…37 Only type IV dyssynergia had a positive likelihood ratio of 2.3, indicative of a "small" increase in the likelihood of disease. 37 …”

“…26 There is substantial agreement among expert observers for the overall diagnosis dyssynergia (kappa = 0.35). 37 However, dyssynergia is not useful for discriminating between healthy people and patients because 90% of healthy volunteers and patients with functional constipation had an abnormal anorectal pressure profile during simulated defecation. 37 Only type IV dyssynergia had a positive likelihood ratio of 2.3, indicative of a "small" increase in the likelihood of disease.…”

“…36 However, several studies have observed that approximately 20% of asymptomatic people have dyssynergic defecation during non-HRM. 37 Likewise, the RAPG during simulated evacuation measured with HR-ARM and HD-ARM is often negative in healthy people. 21,22,26 Indeed, depending on the technique, age and sex, a RAPG as low as -71 mmHg during simulated defecation may be regarded as "normal."…”

What Is New in Rome IV

“…70 Regarding the functional defecation disorders, in the previous classification only patients with functional constipation would be eligible to be diagnosed with a defecatory disorder. However, because it has been recognized that patients with IBS and pelvic floor dysfunction can have an association with dyssynergic dysfunction, 71 and they can be treated with biofeedback irrespective of their association with IBS, 72 IBS-C have now been included in the Rome IV definition. 70 In addition, criteria for inadequate propulsive forces and inappropriate contraction of the anal sphincter and/or pelvic floor muscles are no longer specified because they vary among different techniques.…”

Analysis of Nausea in Clinical Studies of Lubiprostone for the Treatment of Constipation Disorders

“…Previous studies have reported the presence of dyssynergic defecation in 27-59% patients with CIC [14], a condition best assessed using anorectal manometry. Although anorectal manometry may be helpful in defining the causes of constipation in future studies, the technique is not only technically cumbersome and expensive for a large cohort study; there also is lack of consensus on its applicability to constipation management [16]. Although the understanding of defecatory disorders is increasing due to the availability of diagnostic tests, including 3D-transit system imaging and manometry, and magnetic resonance imaging (MRI), on a practical basis, defecatory diaries are the most feasible method for large-study enrollment despite evidence of discordance between patient-reported symptom diaries of constipation and objective measures [17].…”