Comorbidity can be defined most generally as the co-occurrence of two or more mental or physical disorders together. This is one of the critical issues while examining the patient and became an important topic of research to understand the effects in detail. Comorbid indicates existence of different medical conditions within the patient which might be independent or dependent on each other. There is lot of criticism involved with use of term Comorbidity as psychiatrists argue using of these terms will demotivate patient further and can cause adverse effects so they argue use of comorbidity should be avoided.
Definitions Feinstein defined comorbidity as “any distinct clinical entity that has co-existed or that may occur during the clinical course of a patient who has the index disease under study”. Within psychiatry, comorbidity is commonly used to refer to the overlap of two or more psychiatric disorders (Boyd, Burke, Gruenberg, et al. , 1984). Comorbidity between substance use disorders and other mental disorders has gained increasing prominence in psychiatry and psychology within the past few decades (Wittchen, 1996).
Types of comorbidity Researchers have classified Comorbidities into different categories Homotypic comorbidity and heterotypic comorbidity are two types of comorbidities. Co-occurrence of two different substance use disorders e. g. cannabis and alcohol is an example of homotypic comorbidity. Heterotypic comorbidity refers to the co-occurrence of two disorders from different diagnostic groupings this might include, for example, the co-occurrence of a substance use disorder and an anxiety disorder.
The co-occurrence of substance use and other mental disorders has been termed ‘heterotypic’ comorbidity, meaning comorbidity between different classes of mental disorders (Angold, Costello and Erkanli, 1999) Another distinction is made between ‘concurrent’ and ‘successive’ comorbidity. Concurrent comorbidity is that in which two or more disorders are present at the same time, such as schizophrenia and alcohol dependence. Successive comorbidity is defined as comorbidity in which disorders may occur at different times in a person’s life, in ways that may or may not be causally related to each other.
Why study comorbidity? Comorbidity is an important aspect of study for treating patients. Importance of comorbidity can be classified into categories namely importance for treatment, theory, research and prevention. All of these are interrelated like better research helps in treatment and prevention programs and research need to take into consideration the clinical outcomes People with alcohol use disorders often have co-occurring psychiatric disorders, but they frequently do not receive specialized substance abuse treatment that addresses both conditions.
Although pharmacological and psychosocial treatments for alcohol use disorders and psychiatric disorders can be integrated to help these patients, relatively few clinical studies have tested these types of treatments. As mental health and substance abuse facilities expand their services for patients with dual disorders, further research is needed to guide the treatment of this patient population. Reasons for Comorbidity It is observed that there is direct causal relationship between different comorbidities. Mental disorders are subjected to be causing substance disorders like alcohol and drugs.
Also it is observed that substance disorders are causing mental disorders. It can be explained as use of cannabis leads to use of other illicit drugs which might influence a person a lot making him least interested in general activities or social gatherings and tend to stay alone which might finally lead to mental disorders like depression etc. These are the factors which have direct causal relationship there might be other factors which might be unrelated like the genetic disorders or social environment factors leading to comorbidity.
One of the key issues that needs to be understood here is mental disorders cannot be measured by biological tests. Mental disorders are known only through self-report, health utilization data, symptom- or criteria-based scales, or clinical interviews. Self-report and claims use the existing conditions and compare them with general characteristics to make a decision on comorbidity. Comorbidity and Cost Implication Costs in US healthcare in rise from many years and efforts are being made from long time to control the costs.
In the context of controlling the costs it is important to consider comorbidity also an important factor as patients treated with comorbid conditions are generally prone to higher costs than the ones with normal conditions. Analysis has been done for costs associated for patients with Alzheimer disease are analyzed in a research by (Kuo TC1, Zhao Y, Weir S, Kramer MS, Ash AS) it is noted that individuals with AD are more likely to have mental health conditions, neurologic conditions, cognitive disorders, cerebrovascular disease, diabetes with acute complications, and injuries.
Annual costs for AD patients are $3567 (34%) higher than for controls. Excess costs attributable to AD, after controlling for non-AD illness burden, are estimated at $2307 per year with outpatient pharmacy being the key driver ($1711 in excess costs). Clearly it shows there is at least 34% higher costs with comorbid conditions, this might be even higher in conditions like cancer where the comorbid conditions can have diverse effects. So it is important to study comorbid conditions in order to make better judgments to control costs associated with treating diseased.