Patients with anxiety disorders: A challenge for primary care

Anxiety disorders are the most prevalent group of mental disorders in the United States, according to two major epidemiological studies conducted over the past 20 years.

More than 15.7 million people in this country suffer from anxiety disorders alone and another 11.7 million experience both anxiety and one other psychiatric disorder.

The estimated economic burden of anxiety disorders in 1998 was $63.1 billion. Loss of productivity in the workplace, pharmaceutical costs, and mortality costs constitute 15% of the total The largest component of the societal costs of anxiety disorders was found to be nonpsychiatric direct medical costs (primary care settings, emergency room) accounting for 54% of the total, while direct psychiatric costs accounted for an additional 31% (Greenberg et al., 1999).

Because primary care providers carry the burden of recognizing patients with anxiety disorders, these are promising locations for identifying individuals who could benefit from treatment. Therefore, this article focuses on recognition and management of two of the more common anxiety disorders seen in primary care: panic disorder and generalized anxiety disorder.

Illusive Diagnosis

Recognizing anxiety disorders in the primary care setting can be a difficult task because of the association of anxiety with unexplained physical symptoms and/or medical illness.

In specific subsets of patients with unexplained physical symptoms, the rate of anxiety disorders is particularly high. Panic disorder in non-cardiac chest pain and palpitations is 40%-45%; labile hypertension 40%; irritable bowel syndrome 40%; and unexplained syncope, vertigo, and dizziness 20%. Generalized anxiety disorder (GAD) is also over-represented in these areas.

Gastroenterologists are the medical specialists most often seen by patients with GAD, and otolaryngologists and neurologists are most often seen by panic disorder patients (Roy-Byrne & Katon, 2000).

Anxiety can also be a co-morbid complication in diagnosed medical illness. The anxiety may be a response to the illness or may have pre-- existed the illness. Either way, anxiety has the potential to aggravate the medical illness. Recent studies document increased rates of anxiety coexisting in patients with cardiac, gastrointestinal, respiratory, and otoneurologic illness.

The 16% rate of panic disorder in cardiac patients is thought to be higher than the general population. Panic disorder can have potential deleterious effects in the patient with coronary heart disease by increasing smooth muscle contraction, elevating heart rate and blood pressure, and decreasing vagal tone and heart rate variability.

The decreased vagal tone frequently seen in anxiety disorder patients, along with smooth muscle abnormality, may also be a contributing factor in gastrointestinal disorders. Conversely, intermittent intestinal distention as in irritable bowel syndrome can increase the rate of noradrenergic activity ultimately worsening anxiety.

Respiration is particularly unstable in panic disorder. Therefore, it is not surprising that there is an increased rate of anxiety disorders in patients with respiratory disorders, as well as increased rate of respiratory illness in patients with panic.

In early onset respiratory disorders, a conditioning effect may have progressed by repeated episodes of shortness of breath. Also, studies have shown increased carbon dioxide sensitivity in panic disorder, which could explain the development of panic in chronic obstructive pulmonary disease (COPD) patients.

In the area of otoneurologic disorders, studies have shown that 75% of panic patients have an increased rate of abnormal vestibular testing, without diagnosed Meniere's disease or vestibular neuritis. In addition, there is increased rate of panic in those patients with a diagnosed vestibular disease (Roy-Byrne, 2000).

Symptoms

One of the current theories on the development of panic disorder asserts that some individuals have an 44 anxiety sensitivity" to particular somatic symptoms. In addition, the individual believes that the bodily sensations predict a catastrophic outcome. This theory would explain the vulnerability to panic in those with the aforementioned medical illness, and how panic symptoms can be misinterpreted (Bouton, Barlow, & Mineka, 2001).

According to the Diagnostic and Statistical Manual of Mental Disorders (2000), four or more of the following symptoms must occur for the diagnosis of panic disorder:

Palpitations, pounding heart, or accelerated heart rate

Sweating

Trembling or shaking

Sensations of shortness of breath or smothering

Feeling of choking

Chest pain or discomfort

Nausea or abdominal distress

Feeling dizzy, lightheaded, or faint

Derealization (feelings of unreality) or depersonalization (being detached from oneself)

Fear of losing control or going crazy

Fear of dying

Paresthesias

Chills or hot flashes

Panic symptoms characteristically develop abruptly and reach a peak within 10 minutes. Episodes are recurrent and patients begin to worry about having future attacks. Agoraphobia is a frequent complication of panic disorder, as patients begin to fear and avoid situations in which attacks have occurred or where escape may be difficult. Consequently, panic disorder is frequently associated with significant impairment in overall quality of life as it affects social, marital, and vocational functioning (Pollack & Marzol, 2000).