Abstract
Purpose:
Prior research indicates that verbal reports of illness perceptions are associated with quality of life among individuals with interstitial lung disease (ILD). However, individuals with diverse language and verbal abilities may have difficulty providing verbal ratings of illness status. This study evaluated both verbal and visuo-graphic measures of perceived illness as predictors of illness-related quality of life and self-reported pulmonary symptoms among individuals with ILD.
Methods:
This was a cross-sectional study in a convenience sample of patients with ILD recruited from a clinic setting. Forty adults (63% female; mean age: 62.8; range: 32–85 years) with ILD completed standard medical evaluations of pulmonary function and exercise capacity. Study participants also completed self-report questionnaires (pulmonary symptoms, illness-related quality of life, and illness perceptions) and the lung coloring task (LCT), a standardized visuo-graphic measure of illness perceptions developed for this study. The primary approach to data analysis was multiple regression analysis predicting illness-related quality of life and self-rated symptoms from pulmonary function, illness perceptions, and LCT.
Results:
Both forced vital capacity and illness perceptions were significant predictors of illness-related quality of life, accounting for approximately 55% of the variance. The symptom dimension of illness-related quality of life was predicted by forced vital capacity, illness perceptions, and LCT, accounting for approximately 40% of the variance.
Conclusions:
Illness perceptions are important for understanding illness-related quality of life among individuals with chronic lung disease. Visuo-graphic measures of illness perceptions may be especially useful for evaluating symptom experiences in chronic lung disease.
Keywords: dyspnea, illness perceptions, illness-related quality of life, interstitial lung disease, visuo-graphic assessment
Pulmonary function (forced vital capacity) and illness perceptions (both verbal and visuo-graphic measures) predicted illness-related quality of life among patients with interstitial lung disease. Thus, illness perceptions are important for understanding illness-related quality of life in patients with pulmonary disease, and visuo-graphic measures provide a novel approach for assessing illness perceptions
KEY PERSPECTIVE:
What is novel?
Both verbal and visuo-graphic measures of illness perceptions predicted quality of life among patients with lung disease when accounting for an objective measure of pulmonary function.
Visuo-graphic measures of illness perceptions predicted illness-related quality of life when accounting for verbal measures of illness perceptions.
Visuo-graphic measures of illness provide a novel approach for understanding the experience of patients with lung disease.
What are the clinical and/or research implications?
Evaluation of illness perceptions is relatively easy and may provide useful information pertaining to the patient view of their disease.
Because illness perceptions contribute to illness-related quality of life, illness perceptions could be an important target to consider for clinical intervention.
Nonverbal (ie, visuo-graphic) measures of illness may provide additional useful information about the patient’s view of the disease and illness-related quality of life.
Interstitial lung disease (ILD) encompasses over 200 pulmonary diseases characterized by dyspnea, hypoxemia, chronic coughing, and varying degrees of lung inflammation and fibrosis.1 Median survival among patients with a new ILD diagnosis ranges from 3.8 to 7.1 years.2 Shortened life expectancy among patients with ILD underscores the importance of adequately assessing and maintaining quality of life in this group. Prior studies have documented reduced quality of life among patients with ILD3 predicted by poorer objective lung function4 and negative illness perceptions.5
Illness perceptions are described as mental models that evolve in medical patients to help explain their symptoms and medical status. Prior research has documented a range of cognitive domains and emotions reflected in the illness perceptions of patients with various medical conditions, including cardiac disease,6 chronic obstructive pulmonary disease,7 diabetes,8 and breast cancer.9 Primary cognitive components of illness perceptions include perceived sources or causes of the illness, expected duration, effects on the patient’s life, primary symptoms, and the degree to which the illness can be controlled or cured.10 Illness perceptions among medical patients have been associated with important behavioral outcomes, such as adherence to lifestyle recommendations in patients with cardiac disease,11 medication adherence among patients with asthma,12 and both physical and psychological outcomes among patients with chronic obstructive pulmonary disease in pulmonary rehabilitation.13
Although self-report measures of illness perceptions (eg, Brief Illness Perception Questionnaire [BIPQ])14 typically require that respondents provide numerical ratings on various domains of illness, more recent studies have evaluated visuo-graphic methods of determining illness perceptions. Visuo-graphic depictions may be more effective for evaluation of patients with limited reading capacity, for those who have difficulty with verbal processing, or for those who prefer visual response options. Prior studies have found that visuo-graphic measures of illness perceptions are strongly associated with both numerical ratings of illness perceptions and psychological functioning. For example, greater perceived disease severity as measured in drawings of the heart by patients with heart failure was associated with higher levels of anxiety and depression;15 more accurate drawings among patients with lung cancer were associated with poorer illness perceptions;16 and larger drawings of the head among patients with headache were associated with more negative illness perceptions.17 No prior study has evaluated visuo-graphic measures of illness perceptions among patients with ILD or the relationship of visuo-graphic measures of illness with quality of life.
This study was designed to evaluate illness perceptions in a convenience sample of patients with ILD utilizing 2 measures of perceived illness: a widely employed verbal measure and a novel visuo-graphic measure. The goal of the study was to determine the degree to which the visuo-graphic measure of illness perceptions would predict quality of life and symptom experience among patients with ILD above and beyond the verbal measure of illness perceptions. It was hypothesized that more negative illness perceptions, utilizing both verbal and visuo-graphic measures, would predict poorer disease-related quality of life and greater pulmonary symptoms.
METHODS
PARTICPANTS
Participants were recruited from an outpatient clinic for patients with ILD at a major academic medical center. All prospective participants had a confirmed diagnosis of ILD (eg, idiopathic pulmonary fibrosis/interstitial pneumonitis, sarcoidosis, hypersensitivity pneumonitis, cryptogenic organizing pneumonia, drug-induced or other idiopathic ILD), as reflected in imaging scans and/or lung biopsy. Prospective participants were excluded if they were currently pregnant, had an unconfirmed ILD diagnosis or a history of pulmonary transplant, lacked available pulmonary function test data at the time of recruitment, or if they were unable or unwilling to follow the requirements of the study protocol, including written informed consent.
PROCEDURES
All study procedures were approved by The Ohio State University Institutional Review Board. Recruitment was conducted over a 6-month period, at the time of regularly scheduled patient clinic appointments. All prospective participants were given a description of the study, and interested individuals then completed informed consent and a packet of self-report questionnaires. Upon completion of the clinic visit, participants were compensated with a $15 gift card.
MEASURES
Standard spirometric testing was conducted during each participant clinic visit to monitor pulmonary function. Two measures from this testing were utilized to document the severity of ILD,18,19 forced vital capacity (FVC) and diffusing capacity for carbon monoxide (DLCO), both quantified as percent of predicted based on age, sex, and race. At the clinic visit, participants also completed a standardized 6-minute walk test.20
The packet of self-report questionnaires completed by participants included evaluations of disease-related quality of life, pulmonary symptoms, and illness perceptions.
Illness-Specific Quality of Life Measure
The St. George Respiratory Questionnaire (SGRQ) is a widely-used 50-item illness-specific quality of life self-report measure with 3 subscales (Symptoms = 8 items; Activity = 16 items; Impacts = 24 items). Scoring algorithms generate a total score and 3 subscale scores, all ranging from 0 (no impairment) to 100 (maximum impairment), with higher scores indicating greater impact of illness on quality of life.21 Cronbach alpha for the total score was 0.95, and internal reliabilities for Symptoms, Activity, and Impacts subscales were 0.86, 0.94, and 0.87, respectively.
Symptom Measures
The University of California, San Diego Shortness of Breath Questionnaire (SOBQ) is a 24-item measure of reported shortness of breath during routine activities, with each item rated on a 5-point scale from “not at all” to “maximally or unable to do because of breathlessness.” Scores range from 0 to 120, with higher scores reflecting greater shortness of breath.22 The SOBQ has demonstrated excellent internal consistency and external validity. Cronbach alpha for this study was 0.96.
The Leicester Cough Questionnaire (LCQ) is a 19-item self-report measure of chronic cough and related quality of life, with each item rated on a 7-point scale from “none of the time” to “all of the time.” Mean ratings (1–7) are calculated for each of the 3 domains (Physical, Psychological, and Social), and a total score is generated by summing the 3 domain scores. Total scores range from 3 to 21, with higher scores reflecting a lower impact of cough in various aspects of life.23 Cronbach alpha for the total score was 0.96, and internal reliabilities for Physical, Psychological, and Social domains were 0.90, 0.90, and 0.78, respectively.
Health Perception Measures
The BIPQ is a 9-item self-report measure providing ratings for 8 dimensions of illness perceptions: consequences (patient expectations of the outcome of the illness), timeline (expected duration of the illness), treatment control (belief in medical treatment leading to recovery), personal control (belief in individual ability to recover from the illness), identity (how the illness and symptoms are labeled), concern (patient concern about the illness), emotional representations (negative emotional responses to the illness), and illness understanding (how a person makes sense of their illness). The BIPQ is the most widely utilized measure of illness perceptions, with studies conducted among a range of patient groups in various countries around the world.24 The scale has demonstrated test–retest reliability and concurrent validity as well as good discriminant validity.14 Scores for each dimension range from 0 to 10, with scores for personal control, treatment control, and coherence reversed so that higher scores on all dimensions indicate more threatening perceptions of the illness. (For the ninth item on the questionnaire, respondents list the 3 factors they believe to be most important in causing their illness, but these open-ended responses were not analyzed for this study.) Total scores for the 8 items range from 0 to 80, and Cronbach alpha in the current study was 0.54. Prior studies among patients with heart failure25 and cancer26 have documented a “Consequences” subscale of the BIPQ, consisting of 4 dimensions: consequences, identity, concern, and emotional response. Internal reliability of the Consequences subscale in this sample was 0.84. Thus, all study analyses were conducted utilizing both the BIPQ-Total score (8 items) and the 4-item BIPQ-Consequences subscale.
The lung coloring task (LCT) was developed for this study to measure participant visuo-graphic characterization of disease severity as an indicator of illness perceptions. Whereas prior studies of visuo-graphic illness perceptions allowed participants to freely draw a picture of their own organ or body part (eg, heart, lung, and head),15-17 the LCT measure was designed to be more easily replicable and to minimize subjectivity in the scoring procedures. For the LCT, respondents were provided with an outline drawing of the human lungs as shown in Figure 1 and were given the following instructions: “Below is an outline drawing of the human lung. Considering your own pulmonary disease, shade in an area of the lung to indicate how much of your lung you feel is affected by your disease. Note: If you feel your lung is not at all affected by your disease, do not shade in any portion of the lung. However, if you feel your lung is affected by your disease in any way, at least some portion of the lung should be shaded below.” Employing digital planimetry techniques utilized in prior research,27 the SketchandCalc computer program (SketchAndCalc Area Calculator, iCalc) was then used to calculate the area of shaded lung in each drawing. First, undergraduate research assistants were trained in use of the computer program to outline the portion of the lung shaded in each of the drawings and the total area of the lung drawing (ie, both shaded and unshaded). The computer program then used the 2 outlines by the technician to calculate the numerical area of perceived lung disease (in mm2) and the total area of the lung. The area of diseased lung for each drawing was then divided by the total area of the lung to generate a percent “score” indicating the proportion of the lung the participant perceived to be diseased, with higher scores reflecting greater perceived disease severity. All measurements were standardized across participants before scoring. Two independent scores were calculated for each drawing. If there was a difference of more than 10% in the 2 scores, the lung drawing was scored by a third trained technician. Final scores were derived by averaging the 2 closest lung measurements. Interscorer reliability of measurements was excellent (>99%). An example of a drawing by a study participant is included in Figure 2.
Figure 1.
Lung coloring task.
Figure 2.
Example of participant response to lung coloring task.
DATA ANALYSES
Data were analyzed with a series of 9 hierarchical multiple regression analyses predicting SGRQ (Total, Symptoms, Activity, Impacts), SOBQ, and LCQ (Total, Physical, Psychological, Social) from FVC and BIPQ-Total (or BIPQ-Consequences) in the first step of each regression, followed by LCT in the second step. Because FVC is a key clinical measure used in diagnosis and monitoring of ILD, this analytic plan provided a relatively rigorous test of LCT as a predictor when controlling for disease severity and a verbal measure of illness perceptions.
RESULTS
The study included 40 adults (mean age: 62.8 ± 15.4 years; range: 32–85 years) with ILD. The sample was predominantly female (63%). The body mass index of participants ranged from very low normal (19.3 kg/m2) to severe obesity (71.3 kg/m2), but, on average, the sample was in the obese range (mean body mass index = 30.4 ± 10.3 kg/m2). As shown in Table 1, lung capacity and diffusing capacity were below normal, reflected in mean FVC percent predicted of 64.5 ± 17.0 and DLCO of 61.1 ± 17.9. The mean FEV1/FVC ratio (0.80 ± 0.09) was in the normal range, as expected among patients with restrictive lung disease. Six-minute walk distance was consistent with norms for patients with chronic lung disease.28
Table 1.
Descriptive Statistics for Demographic, Health, and Self-Report Data With LCT Correlation in Patients With Interstitial Lung Disease
| Variable | Mean | SD | Range | LCT Correlation |
|---|---|---|---|---|
| Age, yr | 62.8 | 15.4 | 32–85 | −0.13 |
| Body mass index, kg/m2 | 30.4 | 10.3 | 19.3–71.3 | 0.19 |
| FEV1/FVC | 0.80 | 0.09 | 0.51–0.98 | 0.03 |
| FVC, % predicted | 64.5 | 17.0 | 33–107 | −0.43a |
| DLCO | 61.1 | 17.9 | 26–108 | −0.17 |
| Six-minute walk test, ft | 1253 | 426.4 | 492–2169 | −0.02 |
| Time since diagnosis, yr | 4.0 | 3.0 | 0–11 | −0.09 |
| SGRQ-Total score | 45.8 | 20.2 | 2.1–80.6 | 0.47a |
| SGRQ-Symptoms | 44.1 | 23.7 | 0–88.0 | 0.52b |
| SGRQ-Activity | 64.9 | 25.8 | 0–100 | 0.29 |
| SGRQ-Impacts | 34.8 | 19.6 | 0–72.3 | 0.49a |
| SOBQ-Total | 47.7 | 27.4 | 2.0–91.0 | 0.33c |
| LCQ-Total score | 16.4 | 3.9 | 4.8–21.0 | −0.49a |
| LCQ-Physical | 5.2 | 1.2 | 2.1–7 | −0.51b |
| LCQ-Psychological | 5.5 | 1.5 | 1.4–7 | −0.49a |
| LCQ-Social | 5.7 | 1.3 | 1.3–7 | −0.40c |
| BIPQ | 46.6 | 10.0 | 20–68 | 0.49a |
| LCT, % | 19 | 19 | 0–73 |
Abbreviations: BIPQ, Brief Illness Perception Questionnaire; DLCO, diffusing capacity of the lung; FEV1, forced expiratory volume in the first second; FVC, forced vital capacity; LCQ, Leicester Cough Questionnaire; LCT, lung coloring task; SGRQ, St. George Respiratory Questionnaire; SOBQ, University of California San Diego Shortness of Breath Questionnaire.
P < .01.
P < .001.
P < .05.
Comparing self-report questionnaire data from Table 1 to published norms, study participants reported significant reductions in quality of life associated with ILD (SGRQ)29 and impaired functioning due to dyspnea (SOBQ)30 and cough (LCQ-Total score).31 Consistent with their symptom-related responses, the total score for the BIPQ reflected moderate levels of experienced threat from ILD (mean = 46.6 ± 10.0).32 The mean LCT indicated that participants perceived, on average, 19% of the lung to be affected by ILD, but individual percent values ranged from 0% to 73%. As shown in Table 1, the LCT measure was significantly correlated with FVC percent predicted, SGRQ, the symptom measures (SOBQ, LCQ), and BIPQ, but was not associated with DLCO, 6-minute walk distance, years since diagnosis, age, or body mass index.
Regression of SGRQ-Total scores on FVC and BIPQ-Total indicated that both predictors were significant and together accounted for approximately 55% of the variance in SGRQ-Total, as shown in Table 2. When added in the second step, LCT did not contribute to the prediction of SGRQ-Total. Results for BIPQ-Consequences were nearly identical, as shown in Table 2.
Table 2.
Hierarchical Regression of SGRQ-Total on FVC, BIPQ (Total Score and Consequences Subscales), and LCT in Patients With Interstitial Lung Disease
| B | SEB | T Value | β | Adjusted R2 | ∆R2 | |
|---|---|---|---|---|---|---|
| BIPQ-Total | ||||||
| Step 1 | ||||||
| FVC, % predicted | −0.34 | 0.14 | −2.41a | −.27 | 0.55b | |
| BIPQ-Total | 1.29 | 0.23 | 5.68b | .64 | ||
| Step 2 | ||||||
| LCT | 8.05 | 12.5 | 0.65 | .09 | 0.54b | NS |
| BIPQ-Consequences | ||||||
| Step 1 | ||||||
| FVC, % predicted | −0.42 | 0.15 | −2.85c | −.33 | 0.49b | |
| BIPQ-Consequences | 1.26 | 0.26 | 4.93b | .57 | ||
| Step 2 | ||||||
| LCT | 13.81 | 12.8 | 1.08 | .15 | 0.50b | NS |
Abbreviations: B, unstandardized beta; BIPQ, Brief Illness Perception Questionnaire; FVC, forced vital capacity; LCT, lung coloring task; NS, not significant; SEB, standardized error of the unstandardized beta; SGRQ, St. George Respiratory Questionnaire.
P < .05.
P < .001.
P < .01.
Regression of SGRQ-Symptoms scores on FVC and BIPQ-Total indicated that together both predictors accounted for approximately 34% of the variance, as shown in Table 3. When LCT was added in the second step, the full model remained significant (F(3,36) = 9.73, P < .001), and a significant additional 6% of variance was explained (F change(1,36) = 4.65, P = .038). As shown in Table 3, results for BIPQ-Consequences were very similar.
Table 3.
Hierarchical Regression of SGRQ-Symptoms on FVC, BIPQ (Total Score and Consequences Subscales), and LCT in Patients With Interstitial Lung Disease
| B | SEB | T Value | β | Adjusted R2 | ∆R2 | |
|---|---|---|---|---|---|---|
| BIPQ-Total | ||||||
| Step 1 | ||||||
| FVC, % predicted | −0.44 | 0.20 | −2.20a | −.30 | 0.34b | |
| BIPQ-Total | 1.09 | 0.32 | 3.38c | .46 | ||
| Step 2 | ||||||
| LCT | 36.19 | 16.79 | 2.16a | .34 | 0.40b | 0.06a |
| BIPQ-Consequences | ||||||
| Step 1 | ||||||
| FVC, % predicted | −0.51 | 0.20 | −2.52a | −.35 | 0.30b | |
| BIPQ-Consequences | 1.03 | 0.35 | 2.91c | .40 | ||
| Step 2 | ||||||
| LCT | 40.35 | 16.59 | 2.43a | .37 | 0.38b | 0.08a |
Abbreviations: B, unstandardized beta; BIPQ, Brief Illness Perception Questionnaire; FVC, forced vital capacity; LCT, lung coloring task; SEB, standardized error of the unstandardized beta; SGRQ, St. George Respiratory Questionnaire.
P < .05.
P < .001.
P < .01.
Regression of SGRQ-Activity scores on FVC and BIPQ-Total revealed that both predictors together accounted for approximately 39% of the variance (F(2,37) = 13.7, P < .001), but when LCT was added in the second step, no further variance was explained. Similarly, regression of SGRQ-Impacts scores on FVC and BIPQ-Total indicated that together they accounted for 56% of the variance (F(2,37) = 26.2, P < .001), and LCT in the second step explained no further variance. Regression with BIPQ-Consequences as a predictor produced similar results.
Regression of SOBQ scores on FVC and BIPQ-Total revealed that only BIPQ was a significant predictor, as shown in Table 4. When LCT was added in the second step, no further variance was explained, and BIPQ-Total remained the only significant unique predictor of SOBQ. As shown in Table 4, results for BIPQ-Consequences were very similar.
Table 4.
Hierarchical Regression of Dyspnea (SOBQ) on FVC, BIPQ (Total Score and Consequences Subscales), and LCT in Patients With Interstitial Lung Disease
| B | SEB | T Value | β | Adjusted R2 | ∆R2 | |
|---|---|---|---|---|---|---|
| BIPQ-Total | ||||||
| Step 1 | ||||||
| FVC, % predicted | −0.35 | 0.23 | −1.55 | −.20 | 0.38a | |
| BIPQ-Total | 1.52 | 0.36 | 4.18a | .55 | ||
| Step 2 | ||||||
| LCT | −3.28 | 20.03 | −0.16 | −.03 | 0.36a | NS |
| BIPQ-Consequences | ||||||
| Step 1 | ||||||
| FVC, % predicted | −0.41 | 0.21 | −1.95 | −.24 | 0.44a | |
| BIPQ-Consequences | 1.76 | 0.37 | 4.81a | .59 | ||
| Step 2 | ||||||
| LCT | −2.17 | 18.56 | −0.12 | −.02 | 0.42a | NS |
Abbreviations: B, unstandardized beta; BIPQ, Brief Illness Perception Questionnaire; FVC, forced vital capacity; LCT, lung coloring task; NS, not significant; SEB, standardized error of the unstandardized beta; SOBQ, University of California San Diego Shortness of Breath Questionnaire.
P < .001.
Regression of LCQ scores on FVC and BIPQ-Total indicated that only FVC was a significant predictor, as shown in Table 5. When LCT was added in the second step, the full model remained significant (F(3,36) = 5.13, P = .005), and approximately 4% additional variance was explained (F change(1,36) = 2.84, P = .101). Similar results were observed in regressions of the Physical and Psychological dimensions of LCQ, with LCT explaining an additional 5% of the variance in each. However, FVC and BIPQ-Total accounted for approximately 56% of the variance in the Social dimension of LCQ. In turn, when LCT was added in the second step, no further variance was explained. The pattern of results was similar when analyses were conducted with BIPQ-Consequences as a predictor.
Table 5.
Hierarchical Regression of Cough (LCQ) on FVC, BIPQ (Total Score and Consequences Subscales), and LCT in Patients With Interstitial Lung Disease
| B | SEB | T Value | β | Adjusted R2 | ∆R2 | |
|---|---|---|---|---|---|---|
| BIPQ-Total | ||||||
| Step 1 | ||||||
| FVC, % predicted | 0.08 | 0.04 | 2.12a | .32 | 0.20b | |
| BIPQ-Total | −0.12 | 0.06 | −2.02c | −.30 | ||
| Step 2 | ||||||
| LCT | −5.26 | 3.12 | −1.68d | −.30 | 0.24b | 0.04d |
| BIPQ-Consequences | ||||||
| Step 1 | ||||||
| FVC, % predicted | 0.09 | 0.04 | 2.55a | .37 | 0.21b | |
| BIPQ-Consequences | −0.11 | 0.06 | −1.86d | −.27 | ||
| Step 2 | ||||||
| LCT | −5.70 | 2.98 | −1.91d | −.32 | 0.26b | 0.05d |
Abbreviations: B, unstandardized beta; BIPQ, Brief Illness Perception Questionnaire; FVC, forced vital capacity; LCQ, Leicester Cough Questionnaire; LCT, lung coloring task; SEB, standardized error of the unstandardized beta.
P < .05.
P < .01.
P = .05.
P = .10.
DISCUSSION
Illness perceptions were a significant predictor of illness-related quality of life and symptom-reporting among patients with ILD. Both FVC and illness perceptions predicted quality of life and the symptom dimension of quality of life. Illness perceptions uniquely predicted self-reported dyspnea, while FVC was a unique predictor of self-reported cough. Despite the significant correlation between illness perceptions and LCT, LCT contributed additional variance in predicting both SGRQ-Symptoms and self-reported cough. Thus, these data indicate that illness perceptions may be as relevant as objective markers of lung function (FVC) for quality of life among patients with ILD. In predicting dyspnea, illness perceptions were found to be a better predictor than FVC.
These data also indicate that a visuo-graphic measure of perceived illness (LCT) may contribute to symptom-related quality of life above and beyond the influence of lung function and verbal ratings of illness perceptions. In further support of the relevance of LCT, post hoc regression analyses predicting the primary outcomes (SGRQ-Total, SGRQ subscales, SOBQ, LCQ-Total, and LCQ dimensions) from FVC and LCT (ie, without including BIPQ) indicated that only LCT was a significant predictor of SGRQ-Total, SGRQ-Symptoms, LCQ-Total, LCQ-Physical, and LCQ-Psychological. In the absence of a verbal measure of illness perceptions, the visuo-graphic measure was a significant predictor of illness-related quality of life, the symptom dimension of quality of life, and of cough symptoms, especially as coughing influences physical and psychological functioning, but not social functioning.
The visuo-graphic measure utilized in this study improved upon measures used in prior studies because analysis of the visuo-graphic data did not require subjective interpretation. Instead, the procedures (ie, providing a standard image of the lungs and instructing participants to shade the image to reflect their perception of their disease) facilitated the use of a computer program to “score” all images, generating a proportion of diseased lung for each participant. The scoring procedure was standardized, and the reliability of scoring was excellent. In addition, the measure was easily administered in a clinic setting, enhancing the utility of such a measure in a wide range of settings and with a wide range of patients. Thus, this approach may be useful in future studies of patients with a range of pulmonary conditions.
The primary limitation of the study was the use of a convenience sample from a clinic setting. While this strategy facilitated recruitment of participants, it is likely that the sample was not representative of all patients with ILD. In addition, the lower internal reliability of the BIPQ in this study suggested that the total measure may not reflect a unitary construct. However, internal reliability of the 4-item Consequences subscale was acceptable, and data analyses revealed the same pattern of results for both the 8-item Total measure and the Consequences subscale. The sample size was also relatively small, restricting the number of predictors that could be included in the regression models, and the study was limited by the cross-sectional design. It will be important to investigate the degree to which illness perceptions, including measures such as the LCT, predict outcomes over time.
Overall, these data are important in highlighting that cognitive and affective perceptions of illness among patients with ILD are relevant for understanding quality of life and, in some cases, may be as important as objective lung function. As pulmonary rehabilitation becomes more widely utilized among patients with ILD,33 these data may be important for practitioners in the pulmonary rehabilitation setting. While patient beliefs about their illness and their emotional response to it are likely to be highly relevant for quality of life, these data support the utility of a visuo-graphic measure of illness perceptions for further understanding quality of life among patients with chronic lung disease. Competency in psychosocial management of patients in pulmonary rehabilitation requires adequate screening for reduced quality of life.34 As practitioners of pulmonary rehabilitation are faced with larger numbers of patients with diverse (or limited) language and verbal abilities, visuo-graphic measures may provide a useful approach for ensuring an independent evaluation of the patient perception of the illness (ie, evaluation that is not influenced by reliance on an interpreter or other third party) and, in turn, for better understanding the patient’s quality of life.
ACKNOWLEDGMENTS
The authors wish to thank the following individuals for their contributions to this project: Joshua Cermak, MS, Christopher Jurgens, MS, Modio Thiam, Alayna Daniels, Devika Soni, Thomas Jeffrey, and Kelsey Travis.
Footnotes
The authors have no conflicts of interest to report.
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