General medical conditions in 347 bipolar disorder patients: clinical correlates of metabolic and autoimmune-allergic diseases

Abstract

Background: Patients with bipolar disorder (BD) suffer from greater physical morbidity and mortality than the general population. The aim of the present study is to explore the prevalence and clinical correlates of General Medical Conditions (GMC) in a large consecutive sample of patients with BD.

Method: The study sample comprised of 347 patients who met DSM-IV-TR criteria for BD I (n=207, 59.7%), BD II or Cyclothymic Disorder (n=140, 40.3). Diagnostic information was collected by means of the Structured Clinical Interview for DSM-IV Axis I Disorders- Clinical Version (SCID-I), and information about personal and family history were collected by the Semi-Structured Interview for Mood Disorder-Revised (SIMD-R). Standardized procedure was used to assess the diagnosis of GMC, which was considered present only if a specific therapy to treat the condition was prescribed by a specialist or a general practitioner. In order to explore possible relationships between physical comorbidity and clinical features of BD, we compared patients with (MD) and without (No-MD) Metabolic Diseases (MD) and patients with (AAD) and without (No-AAD) Autoimmune-Allergic Diseases (AAD).

Results: The most commonly reported GMCs were: Headache, Hypercholesterolemia (>200mg/dl), Chronic Constipation, Obesity, Arterial Hypertension (BP >140/90 mmHg), Hypothyroidism, Allergic Rhino-Conjunctivitis, Irritable Bowel Syndrome, Hypertriglyceridemia (>150 mg/dl), Metabolic Syndrome, Hiatus Hernia, Dysmenorrhea, Urticaria, Atopic Dermatitis, Psoriasis, Seborrheic Dermatitis, Diabetes Mellitus, Bronchial Asthma, Cardiac Arrhythmias, Biliary Lithiasis, and COPD. In our sample, MD (n=148, 42.7%) and AAD (n=167, 48.1%) were the most common categories of GMCs. Interestingly, the lifetime prevalence of cancer and neoplastic diseases was very low: 1 patient (.3%) reported Lung Adenocarcinoma and 2 (.6%) patients Bowel Cancer. In the group comparisons, length of pharmacological treatment (OR=1.054; 95% CI=1.030-1.078), age at onset of first major episode (OR=1.043; 95% CI=1.019-1.067), length of the current episode (OR=1.025; 95% CI=1.020-1.533) and absence of lifetime comorbid substance abuse (OR=.373; 95% CI=.141-.989) were statistically associated with the presence of comorbid MD; while only AD-induced hypomania (OR=1.62; 95% CI=1.011-2.597), and cyclothymic temperament (OR=1.051; 95% CI=1.016-1.087) were statistically associated with the presence of comorbid AAD.

Limitations: Possible referral and selection bias; retrospective, non-blind, cross-sectional evaluation.

Conclusion: MD and AAD were highly represented in our sample, while cancer and neoplastic diseases were uncommon. The clinical correlates of different sub-groups of GMC suggest different interpretations. The presence of MD seems to be correlated with the progression of BD and the chronic medication exposure, while comorbid AAD seems to correlate with a specific clinical subtype of BD, characterized by mood reactivity and temperamental mood instability. If the link with autoimmune-allergic diathesis will be confirmed, it could provide an interesting new paradigm for the study of the "systemic" nature of mood disorders and a promising target for future treatment options.

Keywords: Autoimmunity; Bipolar disorder; General medical conditions; Metabolic disorders.