Prevention of panic attacks and panic disorder in chronic obstructive pulmonary disease

This study examined whether cognitive behavioural therapy (CBT) could prevent the development or worsening of panic-spectrum psychopathology and anxiety symptoms in chronic obstructive pulmonary disease (COPD). Forty-one patients with COPD, who had undergone pulmonary rehabilitation, were randomised to either a 4 session CBT intervention condition (n = 21) or a routine care condition (n = 20). Assessments were at baseline, post-intervention, and at 6, 12 and 18 months follow-ups. Primary outcomes were the rates of panic attacks, panic disorder, and anxiety symptoms. Secondary outcomes were depressive symptoms, catastrophic cognitions about breathing difficulties, disease-specific quality of life and hospital admission rates. There were no significant differences between the groups on outcome measures at baseline. By the 18 month follow-up assessment, 12 (60%) routine care group participants had experienced at least one panic attack in the previous 6 months, with 2 of these (17%) being diagnosed with panic disorder, while no CBT group participants experienced any panic attacks during the follow-up phase. There were also significant reductions in anxiety symptoms and catastrophic cognitions in the CBT group at all three follow-ups, and a lower number of hospital admissions between 6 and 12 month followups. The study provides evidence that a brief, specifically targeted CBT intervention can treat panic attacks in COPD patients, and prevent the development and worsening of panic-spectrum psychopathology and anxiety symptoms. INTRODUCTION Symptoms of anxiety are common in chronic obstructive pulmonary disease (COPD) and predict worse quality of life and functional level [1]. Many patients with COPD experience panic attacks, which are episodes of intense anxiety accompanied by symptoms of physical arousal [2]. To be diagnosed with panic disorder, patients must experience recurrent panic attacks, anticipatory anxiety about future attacks, and some unexpected and unpredictable attacks (not always in situations inevitably causing dyspnoea in COPD) [2]. The prevalence of panic disorder in COPD has been estimated as up to 10 times greater than the population prevalence of 1.5–3.5% [2, 3]. This high prevalence of panic attacks and panic disorder in COPD is predicted by the cognitive model of panic anxiety [4]. In this model, panic attacks occur in healthy individuals when ambiguous physical sensations like shortness of breath are interpreted in a catastrophic way, such as indicating imminent asphyxia or death. Signs and symptoms of increased physical arousal follow, leading to an escalating cycle that results in panic. In COPD, worsening dyspnoea during physical activity is the defining symptom of an eventually fatal illness. It is easy to understand how vulnerable individuals with COPD, even early in the disease’s course, may overestimate the immediate threat exertional dyspnoea presents and enter the cycle of panic. Anxious and depressive symptoms have been found to worsen over time in COPD patients, and this psychological deterioration has been only weakly correlated with decline in lung function [5]. In addition to affecting quality of life and functional level, anxiety and depression in COPD lead to increased reporting of medical symptoms, increased use of health services, and up to double the health-related costs of patients with COPD alone [6]. Hence, treating anxiety in COPD patients, and so preventing panic disorder, is likely to improve patients’ level of functioning and decrease costs. Cognitive behaviour therapy (CBT) is the treatment of choice for panic disorder in physically healthy adults [7, 8]. Evidence is increasing that CBT produces its effects on panic attacks and panic disorder by decreasing catastrophic beliefs about ambiguous physical sensations [9, 10]. The results of several controlled trials using self-report questionnaires have indicated that CBT can decrease anxiety symptoms in patients with COPD, but the effects of CBT on panic attacks and the development of panic disorder in COPD have not been assessed [11-15]. Intervening early with individuals at risk of panic disorder can prevent the personal and economic effects of the disorder becoming entrenched [16]. In the current study, we therefore evaluated a brief CBT intervention specifically directed at panicrelated anxiety in COPD. The hypothesis was that CBT would be more effective than routine care, which included pulmonary rehabilitation, in preventing the development and/or worsening of panic-spectrum psychopathology and anxiety symptoms in patients with COPD, over an 18 month period. METHODS Study subjects The study was conducted at a teaching hospital in Sydney, Australia. The trial was approved by the University and Hospital Ethics Committees, and all subjects gave written consent. Ninety-six consecutive COPD patients who met the study’s inclusion criteria were identified in the respiratory medicine department’s outpatient clinics, or inpatient ward, and invited to participate. Fifty-two (54%) volunteered. This recruitment rate was similar to the 55% reported by Kunik and colleagues [17]. Baseline assessments were delayed until at least one month after any hospital admission for an infective exacerbation of COPD. All subjects had a diagnosis of moderate to severe COPD [forced expiratory volume in the first second (FEV1) post-bronchodilator <60% predicted and FEV1/forced vital capacity (FVC) < 0.7], corresponding to GOLD stages II or III [18]. They were receiving ongoing outpatient treatment in the respiratory medicine department, where they had also attended an integrated, comprehensive outpatient pulmonary rehabilitation programme. The possible confounding factor of pulmonary rehabilitation attendance, which has been associated with short-term reductions in questionnaire measured symptoms of anxiety and depression, was thus controlled for [19]. All subjects were being treated with a combination LABA/inhaled corticosteroid and a long acting anticholinergic. None was on high dose oral corticosteroids. Exclusion criteria were lack of English literacy (due to the requirement for completion of standardised questionnaires unavailable in other languages), and the presence of any other serious physical illness or psychiatric disorder, including panic disorder. Individuals with panic disorder were excluded because of the study’s preventative focus, and because an extended psychological intervention was considered necessary for such patients [20]. At initial assessment, the Panic Disorder and Agoraphobia sections of the Anxiety Disorders Interview Schedule for DSM-IV (ADIS-IV) were administered, along with relevant questionnaires [21-24]. Eleven individuals were then found ineligible for the study: 9 (17%) were diagnosed with panic disorder and 2 (4%) were diagnosed with major depression. The prevalence of panic attacks (19%, n=10/52)) and panic disorder (17%, n=9/52) at initial assessment were within the ranges expected [3]. Procedure Assignment We used the Excel Bernoulli Function to generate a random sequence of numbers, with a 50% chance of each of the two groups occurring. Randomisation was linked to subject numbers and was concealed until after the baseline assessment was completed. Twentyone participants were randomised to the CBT group and 20 to the routine care group (fig. 1). Assessments Measures were administered at baseline, post-intervention (5–6 weeks later) and at 6, 12 and 18 month follow-up assessments. Pulmonary function tests (FEV1 and FVC) were carried out at baseline by trained laboratory scientists. CBT Intervention The standardised CBT intervention comprised 4, individually administered, one hour sessions. These weekly outpatient sessions commenced within 2 weeks after baseline assessment. The patient manual for the intervention was developed by the first author (NL), an experienced clinical psychologist who also administered the intervention. The manual included strategies effective for the prevention and treatment of panic disorder in younger adults [25]. Adaptations were required for an elderly population with COPD [20, 26-28]. Components of the intervention therefore included: psycho-education about CBT, the effects of the stress response on breathing, and the cycle of panic anxiety in COPD; training in cognitive challenging of unhelpful cognitions; training in “pursed lip breathing”; reinforcement of activity planning and “pacing”; the development of a personalised “good coping plan”; and problem-solving to address any barriers to good coping. The patient manual is available from the first author. Measures Demographics Age, education, occupation before retirement, years since diagnosis of COPD, cigarette smoking history, body mass index, number of days per week when alcohol was consumed, number of alcoholic drinks consumed on these days, incidence of home O2 use, FEV1 post bronchodilator, FVC post bronchodilator, and FEV1/FVC ratio post bronchodilator were recorded. Measures for assessing primary and secondary outcome variables The study’s primary outcome variables were rates of panic attacks and panic disorder, and anxiety symptomatology. Panic attacks and panic disorder were diagnosed with the ADIS-IV, the gold standard clinical interview for diagnosing anxiety disorders [21]. Although panic disorder is more difficult to diagnose when comorbid with respiratory disease, it is identifiable, as mentioned above, when patients have anticipatory anxiety about future panic attacks, and experience some unpredictable attacks not solely precipitated by unavoidable triggers for dyspnoea in COPD (such as physical exertion or infective exacerbations of the disease) [2]. The first author carried out the assessments and intervention, so ADIS-IV interviews were recorded to decrease any possible influence of experimenter bias. Inter-rater reliability was assessed by having another clinical psychologist, blind to treatment condition,