Brief Article
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World J Gastroenterol. Dec 14, 2011; 17(46): 5089-5096
Published online Dec 14, 2011. doi: 10.3748/wjg.v17.i46.5089
Evaluation of latent links between irritable bowel syndrome and sleep quality
Massimo Bellini, Angelo Gemignani, Dario Gambaccini, Simona Toti, Danilo Menicucci, Cristina Stasi, Francesco Costa, Maria Gloria Mumolo, Angelo Ricchiuti, Remo Bedini, Nicola de Bortoli, Santino Marchi
Massimo Bellini, Dario Gambaccini, Cristina Stasi, Francesco Costa, Maria Gloria Mumolo, Angelo Ricchiuti, Nicola de Bortoli, Santino Marchi, Gastrointestinal Unit, Department of Gastroenterology, University of Pisa, 56100 Pisa, Italy
Angelo Gemignani, Danilo Menicucci, Remo Bedini, Institute of Clinical Physiology, National Research Council, 56100 Pisa, Italy
Angelo Gemignani, Danilo Menicucci, Remo Bedini, Extreme Centre, Scuola Superiore S Anna, 56100 Pisa, Italy
Angelo Gemignani, Department of Physiological Science, University of Pisa, 56100 Pisa, Italy
Simona Toti, Italian National Institute of Statistics, 00185 Rome, Italy
Author contributions: Bellini M contributed to patient enrollment, diagnosis of IBS, experimental design, and writing the manuscript; Gemignani A contributed to assessment of sleep disturbances, experimental design, and writing the manuscript; Gambaccini D contributed to patient enrollment, diagnosis of IBS, and writing the manuscript; Toti S and Menicucci D contributed to application of the IRT model and statistical analysis; Stasi C, Mumolo MG and de Bortoli N contributed to patient enrollment and diagnosis of IBS; Costa F performed lower digestive endoscopy in patients > 50 years old to exclude non-functional GI disorders; Ricchiuti A performed in all patients abdominal ultrasonography to exclude non-functional GI disorders; Bedini R contributed to statistical analysis and funded the study; Marchi S contributed to patient enrollment, diagnosis of IBS and funded the study.
Correspondence to: Dr. Massimo Bellini, Gastrointestinal Unit, Department of Gastroenterology, University of Pisa, Via Paradisa No. 2, 56100 Pisa, Italy. mbellini@med.unipi.it
Telephone: +39-50-997448 Fax: +39-50-997398
Received: January 31, 2011
Revised: March 28, 2011
Accepted: April 5, 2011
Published online: December 14, 2011
Abstract

AIM: To examine the links between quality of sleep and the severity of intestinal symptoms in irritable bowel syndrome (IBS).

METHODS: One hundred and forty-two outpatients (110 female, 32 male) who met the Rome III criteria for IBS with no psychiatric comorbidity were consecutively enrolled in this study. Data on age, body mass index (BMI), and a set of life-habit variables were recorded, and IBS symptoms and sleep quality were evaluated using the questionnaires IBS Symptom Severity Score (IBS-SSS) and Pittsburgh Sleep Quality Index (PSQI). The association between severity of IBS and sleep disturbances was evaluated by comparing the global IBS-SSS and PSQI score (Pearson’s correlation and Fisher’s exact test) and then analyzing the individual items of the IBS-SSS and PSQI questionnaires by a unitary bowel-sleep model based on item response theory (IRT).

RESULTS: IBS-SSS ranged from mild to severe (120-470). The global PSQI score ranged from 1 to 17 (median 5), and 60 patients were found to be poor sleepers (PSQI > 5). The correlation between the global IBS-SSS and PSQI score indicated a weak association (r = 0.2 and 95% CI: -0.03 to 0.35, P < 0.05), which becomes stronger using our unitary model. Indeed, the IBS and sleep disturbances severities, estimated as latent variables, resulted significantly high intra-subject correlation (posterior mean of r = 0.45 and 95% CI: 0.17 to 0.70, P < 0.05). Moreover, the correlations between patient features (age, sex, BMI, daily coffee and alcohol intake) and IBS and sleep disturbances were also analyzed through our unitary model. Age was a significant regressor, with patients ≤ 50 years old showing more severe bowel disturbances (posterior mean = -0.38, P < 0.05) and less severe sleep disturbances (posterior mean = 0.49, P < 0.05) than older patients. Higher daily coffee intake was correlated with a lower severity of bowel disturbances (posterior mean = -0.31, P < 0.05). Sex (female) and daily alcohol intake (modest) were correlated with less severe sleep disturbances.

CONCLUSION: The unitary bowel-sleep model based on IRT revealed a strong positive correlation between the severity of IBS symptoms and sleep disturbances.

Keywords: Irritable bowel syndrome; Sleep disorders; Item response theory model; Bayesian model