Medical Co-Morbidities

Definition
Demographic
Description
The Charlson Co-morbidity Index
Co-morbidity of Psychiatry
Co-morbidity of Diabetes
Co-morbidity of Cancer in Elderly Patients

Definition

Morbidity is the presence of a disease state or disorder within a patient. Co-morbidity is the presence of more than one individual disease or disorder within the same patient. It is a state of having multiple distinct medical conditions at the same time.

Demographic

Co-morbidities may be present in anyone regardless of age, but certain populations are more prone to having co-morbidities. Patients that are an advanced age are more vulnerable to medical problems than a younger patient demographic. Certain medical conditions are also prone to association with co-morbidities. For example, diabetes, psychiatric diseases, and cancer (especially in the elderly) are very frequently associated with co-morbid health conditions.

Description

Co-existing or co-morbid conditions are sometimes commonly associated with a particular disease. For example, cancer patients may frequently have coexisting major depression. Diabetes patients may frequently have co-morbidities involving the cardiovascular system, kidney, and the eye. Chronic diseases are often co-morbid with depression.

Having co-morbidities also increases the risks associated with some surgical procedures. Co-morbidities may complicate the diagnosis of a new disease, especially if there are overlapping symptoms between the two. Co-morbidities have an impact on the type of treatment chosen for a patient, as well as the patient’s prognosis. A patient’s disease burden may have a health impact that is greater than the sum of the impact of the individual diseases. The medical outcome of co-morbid conditions may be very severe.

The Charlson Co-morbidity Index

There are many systems that endeavor to standardize the “weight” of the medical impact of different co-morbidities. The end result is to predict the medical outcome or mortality that may result from the presence of specific co-morbidities. There are no systems that have currently been developed that accurately and completely assess this issue and are considered a true medical standard. However, one commonly used system is the Charlson Index, which has been validated and is the most widely accepted of the assessments.

The Charlson Co-morbidity Index attempts to predict the one-year mortality for patients with more than one medical disease or disorder. Each medical condition is categorized according to a set of codes known as the International Statistical Classification of Diseases and Related Health Problems, or ICD Codes. Each ICD Code represents a medical condition and is assigned a specific number that represents the medical weight of the disease. The score assigned to each disease is based on the risk of fatality within one year associated with the disease. Additional points may be added for age, with each decade over forty being one point. The sum of the scores for each co-morbidity gives a total score that represents the risk of dying. The higher the score, the greater the risk of dying. This score assists physicians in determining how to treat patients with multiple co-morbidities. For example, if one patient has cancer, but also very severe co-morbidities, it may not be appropriate to subject the patient to difficult treatments because of the reduced likelihood of survival associated with the co-morbidity.

Co-morbidity of Psychiatry

In psychiatry, a co-morbidity is defined as a diagnosis that exists simultaneously with another diagnosis. However, psychiatric co-morbidities may not represent the presence of multiple disorders. Rather they represent the number of diagnoses necessary to accurately describe the full range of the patient’s symptoms. The severity of a patient’s mental illness has a strong association with the number of co-morbid disorders present. Treatment of psychiatric diseases and disorders are impacted by co-morbidity, as the co-morbidity may render the normal treatment of an illness inappropriate. For example, some pharmaceutical treatments may cause symptoms of anxiety as a side effect. In a patient with an anxiety disorder as a co-morbidity, using this treatment for their primary illness would be inappropriate. Pharmaceutical treatments that have addictive potential are not appropriate for treatment of a primary illness in a patient with drug abuse as a co-morbidity. Drug abuse is often co-morbid with psychiatric disorders, and may be a consequence of the initial illness. Studies have shown that proper treatment of some psychiatric disorders may prevent the development of drug abuse problems.

Providing treatment for patients with co-morbidities that address and do not aggravate all the aspects of their various disorders can be challenging for health care providers. Co-morbidities in psychiatry can be controversial to diagnose as distinct disorders. For example, does a patient with drug abuse problems as well as bulimia (binging on food and then purging through vomiting) have two separate illnesses, or do they have a single disorder involving impulse control? Whether some co-morbidities are truly separate diagnoses or all part of one disorder can be difficult to judge.

Co-morbidity of Diabetes

Diabetes is associated with many different co-morbidities. The increased blood glucose that is part

QUESTIONS TO ASK YOUR DOCTOR

• Do I have co-morbid health conditions?
• Are my co-morbidities truly distinct from each other, or could they be related?
• What can I do to address health concerns regarding my co-morbid conditions?
• Do any of my treatments for primary illness have an adverse impact on one of my co-morbid health conditions?
• Do any of my co-morbidities have an adverse impact on treatment for my primary illness?

of the disease process can be very damaging to the blood vessels and the organ systems. Some of the co-morbidities associated with diabetes were previously believed to be separate from the course of the diabetes disease. It is controversial whether the co-morbidities associated with diabetes are distinct diseases or are a result of the diabetes itself, which is increasingly referred to as “metabolic syndrome”. Regardless of their source, the co-morbidities associated with diabetes have a significant impact on the overall health profile of the patient.

Patients with diabetes often develop vascular complications, which are medical problems of the blood vessels. Damaged blood vessels are a serious complication, as they affect all the organ systems. Excess blood glucose can also directly damage organs. In diabetics, there are often medical complications seen with the kidneys, the retina of the eye, the peripheral nervous system, heart disease, and stroke or peripheral artery disease. Tight control of blood glucose levels may help to prevent the development of complications and these co-morbidities of diabetes.

Co-morbidity of Cancer in Elderly Patients

Patients above 65 years of age statistically bear a large proportion of cancer cases seen in the United States. In addition to cancer, the elderly are vulnerable to many different health conditions such as pulmonary disease, heart disease, and hypertension. Having co-morbidities with cancer has a great impact on decisions made by the patient and the physician regarding treatment choices. When an elderly person is newly diagnosed with cancer and has other existing medical conditions, each health problem needs to be evaluated in the context of its predicted impact on the course of the cancer. Awareness and evaluation of co-

KEY TERMS

Bulimia— Psychiatric disorder involving eating large amounts of food in a short time period and then vomiting to purge the contents of the stomach.

Cardiovascular System— The physiological system including the heart and the blood vessels.

Metabolic Syndrome— A combination of medical disorders including diabetes, high blood pressure, and heart disease.

Pulmonary Disease— Disease involving the lungs.

morbidities is crucial to optimize care of a cancer patient, and may alter the appropriateness of treatment options. Quality of life, limiting the potential complications seen with treatment, and preventing recurrence of cancer are all impacted by how the co-morbidities are managed.

The existence of co-morbidities with cancer also affects the patient’s prognosis for survival. Because of this, physicians must often make treatment choices in the context of the likelihood of survival. For example a physician and patient may need to decide whether it is worth putting the patient through the rigors of chemotherapy, when congestive heart failure may already be severely limiting the patient’s life span in the short term. In some cases, the cancer treatment may cause mortality because of the co-morbidities. The co-morbidity may increase and amplify the adverse effects normally seen with some types of cancer treatment. This may limit the amount of medical assistance available to a cancer patient. Depending on their nature and severity, co-morbidities in cancer may create a far more severe overall health profile and prognosis for a patient.

Resources

BOOKS

Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition, Text Revision (DSM-IV-TR). Washington, DC: American Psychiatric Association; 2000.

Kumar, Vinay, Nelson Fausto, and Abul Abbas. Robbins & Cotran: Pathologic Basis of Disease, Seventh Edition. Saunders, Elsevier, 2005.

The Merck Manual of Diagnosis and Therapy, Eighteenth Edition. 2006.

PERIODICALS

Hall, H., R. Ramachandran, S. Narayan, A. B. Jani, and S. Vijayakumar. “An electronic application for rapidly calculating Charlson comorbidity score.” BMC Cancer 2004; 4(94)doi: 10.1186/1471-2407-4–94

Pincus, H. A., J. D. Tew, M. B. First. “Psychiatric comorbidity: is more less?” World Psychiatry 2004;3(1):18–23.

Yancik, R., P. A. Ganz, C. G. Varricchio, B. Conley. “Perspectives on Comorbidity and Cancer in Older Patients: Approaches to Expand the Knowledge Base.” J Clin Oncol 2001;19:1147–51.

OTHER

Bankhead, Charles. “Comorbidity Can Confound Prostate Cancer Treatment.” MedPage Today. January 22, 2008. http://www.medpagetoday.com/urology/prostatecancer/tb/8061 [Accessed April 15, 2008].

Maria Basile, PhD