The Role of Anxiety Sensitivity in Exercise Tolerance and Anxiety and Depressive Symptoms among Individuals Seeking Treatment in Cardiopulmonary Rehabilitation

Abstract

The aim of the current cross-sectional study was to examine the effects of specific anxiety sensitivity (AS) dimensions (AS -Physical, -Cognitive, and -Social concerns) on exercise tolerance (i.e., 6-minute walk test) and factors that interfere with cardiopulmonary rehabilitation (CPR) and exercise adherence (i.e., depression and anxiety symptoms) among individuals seeking treatment in cardiopulmonary rehabilitation (CPR). Participants were 69 individuals (65.2% male, M_age = 63.60, SD = 12.55, Range = 27-85 years) with various cardiovascular or pulmonary conditions meeting criteria for CPR entry, who presented for an intake appointment at an outpatient phase 2 CPR clinic. Higher levels of AS-Physical and-Social concerns were significantly associated with poorer exercise tolerance and greater generalized anxiety symptoms, respectively. Though none of the AS dimensions were significant individual predictors, they were collectively associated with greater depressive symptoms. Future work should assess whether it may be useful to target AS in some patients prior to or throughout CPR.

Introduction

Cardiopulmonary rehabilitation (CPR) programs are designed to improve exercise tolerance among individuals with cardiopulmonary conditions (Balady et al., 2007; Ries et al., 2007). However, rates of adherence to these programs remains low and less than half of individuals who attend CPR continue to exercise six months following completion of the program (Daly et al., 2002; Moore, Dolansky, Ruland, Pashkow, & Blackburn 2003). Anxiety and depressive symptoms are common among individuals with cardiopulmonary conditions (e.g., Celano & Huffman, 2011; Mikkelsen, Middelboe, Pisinger, & Stage, 2004) and have been shown to reduce adherence to CPR programs and contribute to negative health behaviors, including physical inactivity (Bonnet et al., 2005; McGrady et al., 2009; Moore et al., 2003). To optimize CPR outcomes there is a need to identify factors that may influence exercise tolerance and anxiety and depressive symptoms in this population.

Anxiety sensitivity (AS), or the fear of arousal-related sensations, may be one such factor to examine in this regard (McNally, 2002). AS is a stable, yet malleable, vulnerability factor that amplifies anxious and fearful responding due to the perceived negative physical (AS-Physical), cognitive (AS-Cognitive), and social (AS-Social) consequences of anxiety-related sensations (Taylor et al., 2007). Elevated AS may indirectly contribute to poor CPR progress through negative health behaviors, including physical inactivity. Indeed, individuals with elevated AS avoid physical activity (Hearon et al., 2014; McWilliams & Asmundson, 2001; Moshier et al., 2013; Smits & Zvolensky, 2006), experience higher levels of distress while exercising (Smits, Tart, Presnell, Rosenfield, & Otto, 2010), and have higher levels of perceived exertion during exercise (Farris et al., 2017). Among individuals enrolled in cardiovascular rehabilitation, AS has been shown to be associated with greater fear of exercise (Farris et al, 2018).

The aim of the current study was to examine the effects of AS dimensions in terms of exercise tolerance (i.e., 6-minute walk test) and factors that contribute to poor CPR and exercise adherence (i.e., anxiety and depressive symptoms) among individuals presenting for CPR. Specific AS dimensions were studied to help identify more specific targets to guide future intervention efforts. Consistent with past work in cardiopulmonary populations (Avallone et al., 2012; Farris & Abrantes, 2017; Farris et al., 2018; McLeish et al., 2011), it was hypothesized that, after controlling for the effects of gender, age, and rehabilitation status (cardiovascular or pulmonary), AS-Physical concerns, but not AS-Cognitive or AS-Social concerns, would be associated with higher anxiety and depressive symptoms and poorer and exercise tolerance.

Materials and Method

Participants

See Table 1 for demographic characteristics of the sample. Participants were 69 individuals with various cardiovascular or pulmonary conditions who were referred for an intake appointment at an outpatient phase 2 cardiopulmonary rehabilitation program. All participants in this sample denied current cigarette smoking.

Table 1.

Sample Characteristics

Variable	Cardiovascular	Pulmonary
Gender, % male	67.3	58.8
Age, M(SD)	61.41(12.94)	70.18(8.68)
Race, %
Caucasian	75	70.6
Black/African American	17.3	23.5
Asian	3.8	0
American Indian or Alaska Native	1.9	5.9
Biracial	1.9	0
Not specified	1.9	0
Rehabilitation Status, %	75.4	24.6
Cardiovascular Diagnosis, %
Coronary artery disease	23.1	-
Myocardial infarction	23.1	-
PTCA	23.1	-
Chronic heart failure	13.4	-
Valve replacement	9.6	-
Other cardiovascular	7.6	-
Pulmonary Diagnosis, %
COPD	-	41.2
Idiopathic Pulmonary Fibrosis	-	23.5
Sarcoidosis	-	11.8
Emphysema	-	5.9
Pulmonary Hypertension	-	5.9
Nonspecific Interstitial	-	5.9
Pneumonia	-	5.9
Interstitial Lung Disease	-	5.9

Note. COPD: Chronic Obstructive Pulmonary Disease; PTCA: Percutaneous transluminal coronary angioplasty

Measures

Information from electronic medical records.

Sociodemographic information (i.e., gender, race, and smoking status), primary diagnosis, and baseline assessments from CPR intake appointments (i.e., Patient Health Questionnaire-9 [PHQ-9] and the 6-minute walk test) were collected from each participant’s electronic medical record.

Anxiety Sensitivity Index-3 (ASI-3).

The ASI-3 (Taylor et al., 2007) is an 18-item self-report measure that assesses the degree to which participants fear the negative physical (AS-Physical), social (AS-Social), and cognitive (AS-Cognitive) consequences of anxiety-related symptoms. Internal consistency for each of the three subscales of the ASI-3 in the current study was good (α range = .74-.86).

Generalized Anxiety Disorder-7 (GAD-7).

The GAD-7 (Spitzer et al., 2006) is a 7-item, one-dimensional self-report measure that assesses the presence of generalized anxiety disorder symptoms over the past week. Internal consistency for the GAD-7 in the current study was good (α = .86).

Patient Health Questionnaire-9 (PHQ-9).

The PHQ-9 (Kroenke & Spitzer, 2002) is a 9-item self-report measure that assesses the presence of depressive symptoms over the past two weeks. The total score on the PHQ-9 was extracted from the participant’s medical record, and therefore, internal consistency could not be calculated for the current study.

6-Minute Walk Test (6MWT).

The 6-minute walk test is a valid and reliable tool that is frequently used in clinical research to assesses an individual’s functional exercise tolerance (Butland, Pang, Gross, Woodcock & Geddes, 1982; Guyatt et al., 1985; Hamilton & Haennel, 2000). Participants are asked to walk as quickly as they can along a long corridor for 6 minutes (measured in feet).

Procedure

Study procedures were approved by the Institutional Review Board. Any individual 18 years of age or older presenting to their intake visit at an outpatient phase 2 CPR clinic, regardless of their medical diagnosis, was invited to participate in the study. A waiver of consent was obtained and participants were presented with an information sheet prior to completing study measures. Participants were required to provide verbal consent if they were interested in participating and understood the information sheet before proceeding with the study. As part of the standard CPR intake appointment, individuals completed several self-report questionnaires and physical health examinations—this information was extracted from medical record. In addition to standard intake procedures, participants also completed the ASI-3 and GAD-7.

Data Analytic Approach

First, bivariate correlations were computed to examine the relationships between all study variables. Second, separate hierarchical multiple regression models were constructed for anxiety symptoms (GAD-7), depressive symptoms (PHQ-9), and exercise tolerance (6-minute walk test). In step one of each model, the covariates of gender, age and rehabilitation status (i.e., cardiovascular and pulmonary rehabilitation) were entered. AS-Physical, -Cognitive, and –Social concerns were simultaneously entered in step two of the model.

Results

Descriptive data and bivariate associations between predictor and criterion variables are presented in Tables 2 and 3, respectively.

Table 2.

Descriptive Data for all Study Variables

	Pulmonary (N = 17)			Cardiovascular (N = 52)			Total (N = 69)
	Mean	SD	Range	Mean	SD	Range	Mean	SD	Range	t	p
AS-Physical	2.71	2.95	0-8	5.28	4.81	0-20	4.63	4.53	0-20	2.07	.04*
AS-Cognitive	1.29	1.93	0-7	1.65	2.33	0-10	1.56	2.23	0-10	.57	.57
AS-Social	2.00	2.39	0-7	3.65	3.73	0-19	3.26	3.52	0-19	1.67	.10
Anxiety symptoms	2.88	3.57	0-11	3.33	3.74	0-15	3.21	3.67	0-15	.43	.67
Depressive symptoms	8.36	4.59	1-17	4.98	3.75	0-18	5.57	4.08	0-18	3.78	<.01**
Exercise tolerance	1056.29	378.02	400-1980	1464.13	378.15	555-2110	1365.87	413.33	400-2110	−2.61	.01*

Note. t = independent samples t-test comparing individuals with cardiovascular and pulmonary conditions; AS-Physical: Anxiety Sensitivity Index 3-Physical Concerns (Taylor et al., 2007); AS-Cognitive: Anxiety Sensitivity Index 3-Cognitive Concerns (Taylor et al., 2007); AS-Social: Anxiety Sensitivity Index 3-Social Concerns (Taylor et al., 2007); Anxiety symptoms: Generalized Anxiety Disorder-7 (Spitzer et al., 2006); Depressive symptoms: Patient Health Questionnaire-9 (Kroenke & Spitzer, 2002); Exercise tolerance: 6-minute walk test.

^**= p < .01

^*= p < .05

Table 3.

Intercorrelations among Predictor and Criterion Variables

	1	2	3	4	5	6	7	8	9
1. Gender	-	−.09	.90	.22	.13	−.08	.16	.08	.35**
2. Age		-	.31*	−.22	.01	−.19	−.24	.08	.45**
3. Rehab Status			-	−.25*	−.07	−.20	−.05	.32*	−.42**
4. AS-Physical				-	.56**	.32**	.30*	.20	−.19
5. AS-Cognitive					-	.33**	.25*	.26*	−.05
6. AS-Social						-	.44**	.21	.19
7. Anxiety symptoms							-	.51**	−.01
8. Depressive symptoms								-	−.21
9. Exercise tolerance									-

Note. Gender, 1 = male, 2 = female; Rehab Status: Rehabilitation Status, 1 = cardiovascular rehab, 2 = pulmonary rehab

^**= p < .01

^*= p < .05

Results from the regression analyses are presented in Table 4. In terms of anxiety symptoms, step one of the model was not significant. Step two of the model accounted for 19.9% of variance, and AS-Social was the only significant variable.

Table 4.

Anxiety Sensitivity Predicting Anxiety Symptoms, Depressive Symptoms and Exercise Tolerance

	ΔR2	t (each predictor)	β	sr2	p
Criterion Variable: Anxiety Symptoms
Step 1	.07				.22
Gender		1.07	.14	.02	.28
Age		−1.52	−.21	.04	.12
Rehab Status		.11	.01	.00	.92
Step 2	.20				<01**
AS-Physical		.89	.14	.01	.38
AS-Cognitive		.18	.03	.00	.86
AS-Social		3.05	.39	.13	<.01**
Criterion Variable: Depressive Symptoms
Step 1	.11				.10
Gender		.39	.05	.00	.70
Age		.07	.01	.00	.95
Rehab Status		2.40	.33	.10	.02*
Step 2	.15				.03*
AS-Physical		1.29	.20	.02	.21
AS-Cognitive		.50	.08	.00	.62
AS-Social		1.77	.24	.05	.08
Criterion Variable: Exercise Tolerance
Step 1	.40				<.01**
Gender		−3.12	−.32	.13	<.01**
Age		−3.57	−.39	.13	<.01**
Rehab Status		−2.72	−.30	.08	<.01**
Step 2	.15				<.01**
AS-Physical		−4.13	−.50	.14	<.01**
AS-Cognitive		1.99	.23	.03	.051
AS-Social		.86	.09	.01	.40

^**= p < .01

^*p < .05

Note. β = standardized beta weight; sr² = squared semi-partial correlation.

In terms of depressive symptoms, step one of the model was not significant. Step two of the model accounted for 15.2% variance, though there were no significant individual variables.

In terms of exercise tolerance, step one of the model accounted for 39.5% of variance, and gender, age, and rehabilitation status were significant variables. Step two of the model accounted for an additional 14.4% of variance, and AS-Physical was the only significant variable.¹

Discussion

Consistent with the hypothesis, greater levels of AS-Physical concerns, but not AS-Cognitive or AS-Social concerns, was associated with poorer exercise tolerance. This finding is consistent with past work on AS and exercise (Hearon et al., 2014; McWilliams & Asmundson, 2001; Moshier et al., 2013; Smits & Zvolensky, 2006) and suggest that individuals with cardiopulmonary conditions who fear arousal-related physical sensations are more likely to be physically deconditioned upon entering CPR. It may be the case that individuals with cardiopulmonary conditions, who are high in AS, experience distress when exertion-related symptoms (e.g., breathlessness) are elicited during exercise, resulting in avoidance of exercise, reduced adherence to CPR, and decreased exercise capacity over time (Smits et al., 2010).

Inconsistent with the hypothesis, AS-Social concerns, but not the other AS dimensions, was significantly associated with greater anxiety symptoms. In line with past work (e.g., Allan, Capron, Raines, & Schmidt, 2014; Naragon-Gainey, 2010), this may be due to the fact that the current study assessed generalized anxiety specific symptoms (i.e. GAD), as opposed to anxiety symptoms more globally, or other anxiety disorder-specific symptoms (e.g., panic symptoms). It is also possible that the high correlation between the AS-Physical and -Cognitive dimensions created a suppression effect in the regression models, resulting in the AS-Social concerns dimension emerging as the only significant variable. Also inconsistent with the hypothesis, despite significance when taken together, none of the individual AS dimensions were significantly associated with depressive symptoms. It may be the case that each AS dimension is of equal importance for depressive symptoms in this population. Taken together, it is possible that elevated depressive and anxiety symptoms may hinder CPR treatment progress through reduced exercise adherence and unhealthy lifestyle behaviors (Bonnet et al., 2005; McGrady et al., 2009). Therefore, future research should examine whether reducing AS leads to downstream improvements in these outcomes.

Limitations to the current study include the cross-sectional nature of the design, small sample size, the self-selected nature of the sample, and the homogeneity of the sample in regards to race and ethnicity. Moreover, other theoretically relevant variables that may affect the relationship between AS and exercise tolerance and anxiety/depressive symptoms (e.g., negative affect, disease severity/physical health status, exercise risk status) were not included in the current study in order to minimize participant and staff burden in the CPR clinic. Lastly, though there is considerable overlap in cardiovascular and pulmonary conditions, AS may be differentially associated with exercise tolerance and anxiety/depressive symptoms within each rehabilitation group. Indeed, there were different symptom loads in some areas for individuals with cardiovascular compared to pulmonary conditions. Therefore, future studies with larger sample sizes should examine these relationships separately in cardiovascular and pulmonary patients.

Despite these limitations, findings suggest that the AS, particularly the Physical and Social concerns domains, are associated with poorer exercise tolerance and higher and depressive and anxiety symptoms among individuals with cardiopulmonary conditions seeking treatment in CPR. Though more work is needed, it may be useful to target AS in some patients prior to or throughout CPR.