J Affect Disord. 2014 Dec;169:170-8. doi: 10.1016/j.jad.2014.08.025.
Bipolar disorder and comorbidity: increased prevalence and increased relevance of comorbidity for hospital-based mortality during a 12.5-year observation period in general hospital admissions.
- 1Department of Psychiatry, University of Bonn, D-53105 Bonn, Germany. Electronic address: firstname.lastname@example.org.
- 2Department of Psychiatry, University of Bonn, D-53105 Bonn, Germany; Department of Psychiatry, Radbourne Unit Royal Derby Hospital, Uttoxeter Road, Derby, United Kingdom.
Bipolar disorder (BD) is associated with an increase of psychiatric and physical comorbidities, but the effects of these disorders on general hospital-based mortality are unclear. Consequently, we investigated whether the burden of comorbidity and its relevance on hospital-based mortality differed between individuals with and without BD during a 12.5-year observation period in general hospital admissions.
During 1 January 2000 and 30 June 2012, 621 individuals with BD were admitted to three General Manchester Hospitals. All comorbidities with a prevalence ≥1% were compared with those of 6210 randomly selected and group-matched hospital controls of the same age and gender, regardless of priority of diagnoses. Comorbidities that increased the risk for hospital-based mortality (but not mortality outside of the hospitals) were identified using multivariate logistic regression analyses.
Individuals with BD had a more severe course of disease than controls that was associated with a higher total number of in-hospital deaths. Individuals with BD compared to controls had a substantial higher burden of comorbidities, the most frequent comorbidities included asthma, type-2 diabetes mellitus (T2DM), and alcohol dependence. 18 other diseases with a surplus of diabetes related complications were also increased. Fourteen comorbidities contributed to the prediction of hospital-based mortality in univariate analyses. Risk factors for hospital-based mortality in multivariate analyses were ischemic stroke, pneumonia, bronchitis, chronic obstructive pulmonary disease, T2DM, and hypertension. The impact of T2DM on hospital-based mortality was higher in individuals with BD than in controls.
The study design was not assigned to assess the type of BD, the current bipolar status, and if individuals with BD were treated with medication. It was neither possible to compare drug effects, nor to compare the adherence to treatment between samples.
In one of the largest samples of individuals with BD in general hospitals, the excess comorbity in individuals with BD compared to controls is in particular caused by asthma and T2DM. T2DM and its complications cause significant excess hospital-based mortality in individuals with BD.
Bipolar disorder; Comorbidity; General hospitals; Mortality; Risk factors
Mortality studies report the all cause mortality rate in bipolar disorder (BD) to be two times increased compared to the general population (Schoepf et al., 2014). The presence of physical morbidity in individuals with BD may is associated with a more severe bipolar illness course that may contributes to the worsening of the mortality gap between individuals with bipolar disorder and the general community (Schoepf & Heun, 2015). Non-suicide related mortality risk factors of premature death represent physical diseases that are either related to intravenous street drug use of younger bipolar individuals such as HIV- and hepatitis C infections or to physical conditions that usually become prevalent in older individuals with BD, such as cardiovascular diseases, type-2 diabetes mellitus (T2DM), chronic obstructive pulmonary disease, pulmonary embolism, and dementia. T2DM in BD may represent a mediating variable that is related to the risk of general hospital based mortality. However, the risk factors for general hospital-based mortality are unclear. Thus our study was intended to determine which specific mental and physical comorbidities contribute to later in-hospital deaths in individuals with BD, and whether the risk factors for hospital-based mortality differ for individuals with BD in comparison with hospital controls. In our view our study has the advantage that a representative and relevant control sample was used and that the most relevant outcome from comorbidity, i.e. mortality was addressed.
We found that the excess comorbidity in individuals with BD compared to controls was in particular caused by asthma and T2DM (Figure 1).
Among individuals with BD who died hypertension and T2DM were found to be the most common comorbidities contributing in 35.0% and 25.0% to the prediction of in-hospital deaths, i.e. only 17.6%, and 11.2% of individuals with BD with these comorbidities did not die in the hospitals (Figure 2).
In addition, T2DM in individuals with BD represented a major risk factor for general hospital-based mortality with excess mortality of acute T2DM, as well as of other diabetic related complications (Figure 3).
Our study gives support for an aggressive multidisciplinary approach to identify and treat T2DM to prevent diabetic, respiratory and vascular complications in all individuals with BD.
- Schoepf D, Heun R (2015) Comorbid medical illness in bipolar disorder. British Journal of Psychiatry 206: 522-523.
- Schoepf D, Uppal H, Potluri R, Heun R (2014) Physical comorbidity including type-2 diabetes mellitus as a predictor of mortality in bipolar patients: a naturalistic 12-year follow-up in general hospital admissions. European Psychiatry 29 (1): 1.