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(Chest. 2004;125:106-111.)
© 2004 American College of Chest Physicians

Airway Obstruction Is Common but Unsuspected in Patients Admitted to a General Medicine Service*

David Zaas, MD; Robert Wise, MD, FCCP and Charles Wiener, MD, FCCP; for the Longcope Spirometry Investigation Team*

* From the Longcope Medical Firm, Osler Medical Service, Johns Hopkins Department of Medicine, Baltimore, MD.

Correspondence to: Charles Wiener, MD, FCCP, Director, Osler Medical Housestaff, Johns Hopkins School of Medicine, 1830 East Monument St, Room 9030, Baltimore, MD 21205; e-mail: cwiener{at}jhmi.edu


   Abstract
TOP
 Abstract
Introduction
 Materials and Methods
 Results
 Discussion
 Appendix
 References
 
Study objectives: Obstructive lung disease (OLD) is a worldwide health problem with major impact on health and economics, and can be easily diagnosed by spirometry. Recent expert panels have emphasized the underreporting and underrecognition of this condition. The goal of this study was to measure the prevalence of airway obstruction in patients admitted to an urban teaching hospital and to determine the frequency of a diagnosis of OLD at admission or discharge.

Methods: Prospective study of 153 patients admitted to a medicine service at the Johns Hopkins Hospital in Baltimore, MD. Patients completed bedside spirometry and a questionnaire.

Results: Twenty-six percent of patients had airway obstruction (FEV1/FVC < 70%), including 6% with a very severe airway obstruction (FEV1 < 30% predicted). At hospital discharge, a clinical diagnosis of OLD was present in only 33% of patients with mild airway obstruction (FEV1 > 70% predicted), 30% of patients with moderate airway obstruction (FEV1 50 to 69% predicted), 33% of patients with severe airway obstruction (FEV1 30 to 49% predicted), and 89% of patients with very severe airway obstruction (FEV1 < 30% predicted). Only 40% of patients with airway obstruction were receiving bronchodilator medication at hospital admission or discharge.

Conclusions: Airway obstruction is common in hospitalized patients and is usually undiagnosed and untreated. Spirometry may be a useful component of the examination of hospitalized medical patients to identify OLD.

Key Words: airway obstruction • COPD • FEV1 • FVC • obstructive lung disease • spirometry


   Introduction
TOP
 Abstract
 Introduction
Materials and Methods
 Results
 Discussion
 Appendix
 References
 
The morbidity and mortality of obstructive lung diseases (OLD) continue to rise throughout the world. In the United States, asthma and COPD, which are characterized by airflow obstruction, affect approximately 30 million people and constitute the fourth leading cause of death.1 2 3 4 COPD is the only leading cause of death with an increasing prevalence in the United States; it accounts for > $30 billion per year in direct medical expenditures, and approximately $10 billion per year in lost work.5 6 7 Airflow obstruction, the hallmark of OLD, and specifically a low FEV1, are important predictors of overall mortality, independent of age and smoking status.8 9 10 11 12 13 The prevalence of airflow obstruction in the general population has been estimated to range from 4 to 14%.5 14 15 16 Yet, as stated in the recent Global Initiative for Chronic Obstructive Lung Disease (GOLD) workshop summary, "COPD fails to receive adequate attention from the health care community and government officials."5

The identification of airflow obstruction is essential for identifying patients who may have OLD. Early diagnosis of OLD may have important benefits to patients, allowing for initiation of pharmacologic treatments, of appropriate immunizations, and of behavioral interventions. The objectives of the GOLD project are "to increase awareness of COPD and decrease mortality from this disease."5 Clearly, this will require physicians to identify patients with airflow obstruction who are at risk for OLD. The National Lung Health Education Program17 suggested that primary care physicians should obtain screening spirometry in patients at high risk for OLD.

Hospital admission often presents an opportunity to perform a comprehensive evaluation of general health status. Curiously, while screening tests are often performed for cardiac, endocrine, hepatic, oncologic, and renal disease, the only routine pulmonary screening test is a chest radiograph, which is of little diagnostic value in the absence of symptoms.18 Admission to the hospital presents an opportunity to perform spirometry and to consider intervention if previously unknown airflow obstruction is discovered, particularly in patient populations who underuse primary care physicians or have decreased access to medical services due to socioeconomic reasons.

This study was conducted in order to determine the prevalence of airway obstruction in patients admitted to the general medical service of an urban hospital that provides the majority of primary care to a socioeconomically disadvantaged population, and to determine how frequently patients identified as having airway obstruction have a diagnosis of OLD at hospital admission and at discharge.


   Materials and Methods
TOP
 Abstract
 Introduction
 Materials and Methods
Results
 Discussion
 Appendix
 References
 
Patients admitted to the Longcope Firm of the Osler Medical Service at Johns Hopkins Hospital were eligible for the study. The Osler Medical Service is a general medical service in an inner-city teaching hospital in Baltimore, MD. The Institutional Review Board approved the study protocol, and all participants gave written informed consent. Between March and September 2000, there were 62 days that a resident co-investigator who was not participating in patient care was available to enroll patients into the study. On those days, the resident asked all patients admitted to the Longcope Service in the past 24 h to undergo spirometry and answer a questionnaire. Patients were eligible for enrollment regardless of their admitting diagnosis, including the presence or absence of known lung disease. The only patients who were not asked to participate were those who transferred to the general medical floor from an ICU. A resident co-investigator subsequently reviewed the admission note and discharge summaries of patients enrolled in the study.

A total of 210 patients were asked to participate in the study; 22 patients (10.5%) chose to not participate. In addition, 35 patients (16.7%) were excluded because they could not perform technically satisfactory spirometry or were unable to answer the questionnaire. One hundred fifty-three patients (72.9%) completed spirometry and answered a questionnaire on their first or second hospital day.

Demographic information was collected from the housestaff admission note and from the attending discharge summary. Information abstracted from the hospital admission note included prior diagnosis of lung disease, respiratory symptoms, and chest physical examination findings. Discharge summaries provided the following information: age, race, gender, length of stay, hospital mortality, comorbid conditions, discharge diagnosis, medications, as well as tobacco and illicit drug use history. Race was recorded and classified as white or nonwhite (97% African American). The clinical diagnoses of emphysema, chronic bronchitis, and asthma were abstracted from the hospital admission or the discharge note and were grouped together as OLD. The patient questionnaire inquired about prior diagnosis of lung disease, tobacco and illicit drug use history, and with access to medical care.

Study participants underwent bedside spirometry with a Stead-Wells spirometer (Warren Collins; Braintree, MA) while seated in their hospital room. All resident co-investigators completed a training session in spirometry. Each patient completed three to nine forced expirations to measure the FEV1 and FVC. Adequate spirograms met the criteria as stated in the American Thoracic Society (ATS) guidelines.19 All spirograms were interpreted by a single investigator (D.Z.), who was unaware of the clinical history or the results of the questionnaire. Airway obstruction was defined as FEV1/FVC < 70%. Severity of airway obstruction was based on the percentage predicted of the normal FEV1 as determined by published prediction equations utilizing patient reported height, age, and gender.20 Severity of obstruction was classified as mild (FEV1 > 70% predicted), moderate (FEV1 50 to 69% predicted), severe (FEV1 30 to 49% predicted), or very severe (FEV1 < 30% predicted). The spirometry results were not routinely given to the treating physicians; however, they were free to order spirometry from the hospital pulmonary laboratory in accordance with their usual clinical practice.

Classification data were analyzed using {chi}2 test or Fisher exact test (Minitab Statistical Software, Version 12.23; Minitab; State College, PA) Continuous variables were analyzed using two-tailed t tests. Statistical significance was inferred at p < 0.05.


   Results
TOP
 Abstract
 Introduction
 Materials and Methods
 Results
Discussion
 Appendix
 References
 
A total of 153 patients completed spirometry and the questionnaire. The patients were predominantly middle-aged African Americans with a high prevalence of comorbid medical conditions (Table 1 ). Only 1.9% (3 of 153 patients) were admitted for an asthma exacerbation, and 3.3% (5 of 153 patients) were admitted for a COPD exacerbation as their principal diagnosis. Demographic information was analyzed for the patients who were unable to complete the study to compare them with those who were able to participate. Patients who were unable to complete the study were older, with a mean age of 60.1 years vs 52.1 years (p = 0.025). Patients who were unable to complete spirometry also had a longer length of hospital stay, 9.3 days vs 5.1 days (p = 0.01). No other significant differences were identified between these groups.


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  		Table 1.. Patient Characteristics*

 
Overall, 26% (40 of 153 patients) who completed spirometry had airway obstruction with FEV1/FVC < 70%. When stratified by severity, 5.9% (9 of 153 patients) tested had very severe airway obstruction, 9.8% (15 of 153 patients) had severe airway obstruction, 6.5% (10 of 153 patients) had moderate airway obstruction, and 3.9% (6 of 153 patients) had mild airway obstruction. Patients with airway obstruction were older than patients without airway obstruction (57.6 years vs 49.6 years, p = 0.011) [Table 2 ]. The prevalence of airway obstruction was 34% (33 of 97 patients) for those > 45 years old vs 12% (7 of 56 patients) for those < 45 years old. There was no significant difference in the prevalence of airway obstruction in men compared to women. Obstruction was less common in HIV-positive patients and those with a history of illicit drug use, who were also younger. There was a high prevalence of prior or current cigarette smokers in both patients with and without airway obstruction (62.5% vs 65.5%, respectively; p = 0.88).


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  		Table 2.. Characteristics of Patients With and Without Airway Obstruction*

 
Less than one half (14 of 40 patients; 35%) with airway obstruction had a diagnosis of OLD (COPD, emphysema, chronic bronchitis, or asthma) at the time of hospital admission (Table 3 ). The likelihood of correctly identifying patients with OLD improved only slightly during the hospitalization, as only an additional four patients were identified at discharge. Therefore, only 45% (18 of 40 patients) with airway obstruction had a diagnosis of OLD at discharge. Similarly, 35% (14 of 40 patients) with airway obstruction were being treated with inhaled bronchodilators at hospital admission or at discharge. The ability to identify patients with OLD from the hospital admission note or discharge summary was poor except for patients with very severe airway obstruction (Fig 1 ). Thirty-three percent (2 of 6 patients) with mild airway obstruction, 30% (3 of 10 patients) with moderate airway obstruction, 33% (5 of 15 patients) with severe airway obstruction, and 89% (8 of 9 patients) with very severe airway obstruction had a diagnosis of OLD at the time of discharge.


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  		Table 3.. Clinical Features of Obstructive Ventilatory Defects

 


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  		Figure 1.. Frequency of clinically recognized OLD based on the severity of airway obstruction.

 

   Discussion
TOP
 Abstract
 Introduction
 Materials and Methods
 Results
 Discussion
Appendix
 References
 
The major finding of this study is the high prevalence of airway obstruction in patients admitted to a general medical service in an urban setting. Many of these patients had moderate to very severe obstructive defects. Furthermore, the majority of patients with airway obstruction did not have a diagnosis of OLD and were not receiving therapy for airway obstruction at the time of hospital admission or at discharge. Thus, spirometry provided important clinical information for many patients and hospital admission was a valuable sentinel event to identify these patients.

Overall, the 26% prevalence of airway obstruction in this population is substantially greater than previous estimates in community dwellers, which found airways obstruction in only 4 to 14%.15 16 There are several plausible explanations for the greater prevalence of airway obstruction in our population. Our hospitalized population was older than community populations in other studies. Inner-city populations may have a greater prevalence of OLD, secondary to increased environmental or occupational exposures.21 The low socioeconomic status of East Baltimore may also contribute to the high prevalence of OLD.22 This relatively high prevalence was not, however, the result of large numbers of patients admitted for recognized exacerbations of asthma or COPD, which were diagnosed in only 5.2% of the enrolled patients. We could not attribute this high prevalence of airway obstruction to poor quality spirometry, as all of the included study patients performed spirometry that met ATS standards for acceptable quality and reproducibility.19

All definitions of COPD include airway obstruction as a component of the diagnosis; however, the ATS, European Respiratory Society, and GOLD differ slightly in the importance of clinical symptoms and airflow obstruction reversibility to the diagnosis of COPD.23 In this study, we did not perform repeated spirometry after bronchodilators, nor did we attempt to make new diagnoses of COPD. We only evaluated patients for airway obstruction and the presence of a documented COPD diagnosis at hospital admission or discharge.

The majority of patients with airway obstruction were not characterized as having OLD by their physicians at the time of hospital admission or discharge. Our study did not attempt to correlate airway obstruction with clinical symptoms. Patients with less severe COPD are more likely to be unaware of their disease and are unlikely to consult a physician until their lung disease impairs their quality of life.24 Further, physical examination is not a good tool for identifying patients with airway obstruction.25 General population surveys find only 40% of community dwellers with airway obstruction diagnosed with OLD.15 In our study, only patients with very severe airway obstruction were likely to be identified as having OLD. The percentage of patients with airway obstruction receiving inhaled bronchodilators was similarly small. Therefore, many patients had undiagnosed and untreated OLD, which may have important functional implications.5

There was a high prevalence (5.9%) of admitted patients with very severe airway obstruction (FEV1 < 30% predicted). The third National Health and Nutrition Examination Survey database found very severe airway obstruction in only 0.5% of the general population in the United States.5 15 Severe airway obstruction may predispose patients to be hospitalized for other medical conditions in addition to COPD, which may account for the higher prevalence in our population vs the general population. This group of patients is important to identify because patients with severe airway obstruction are the largest consumers of health-care resources among patients with OLD.5

The percentage of patients who reported they were former or current smokers was high compared to the general population.5 15 Sixty-five percent of the hospitalized patients enrolled in the study were current or former smokers, compared to about 36% in the general US population.26 Although overall smoking has decreased during the last several decades, the prevalence is higher in lower socioeconomic groups. Also, smokers may be more likely to be hospitalized for nonrespiratory medical problems. Airway obstruction was found in both smokers and nonsmokers in approximately equal frequencies. We did not find an association between smoking and the presence of airway obstruction, presumably because of the very high prevalence of smoking and the imprecise recording of tobacco exposure. The use of self-reported smoking history obtained from medical records is often inaccurate.27 This finding suggests that in-hospital spirometry to detect previously unsuspected airway obstruction should not be confined to self-reported cigarette smokers.

The failure to diagnose OLD in a majority of patients found to have airway obstruction identifies the need for an appropriate diagnostic test for this common disease. The high prevalence of airway obstruction in hospitalized patients, especially individuals > 45 years old, suggests that spirometry should be considered as a component of the admission history and physical examination. The benefits of identification of airway obstruction and possible OLD are multiple. The initiation of pharmacological treatment with inhaled bronchodilators can decrease dyspnea, improve independence with activities of daily living, and increase quality of life.5 28 Appropriate vaccinations can be administered for influenza and Streptococcus pneumoniae. Elderly patients often limit their activities because they feel that dyspnea is an expected consequence of aging, whereas it may be a manifestation of OLD. Pulmonary rehabilitation can be considered for patients with severe exercise limitation, thereby improving quality of life and decreasing future hospitalizations.5 29 Currently, the most important benefits of early identification of OLD are smoking-cessation intervention, which can effectively stop the progression of COPD, and administration of bronchodilators, which can improve airflow obstruction.5

An inpatient hospitalization not only provides an opportunity to identify airway obstruction in a subset of high-risk patients, but also provides an opportunity for interventions that may decrease the high morbidity and mortality associated with OLD. This study was conducted in an inner-city teaching hospital with a high prevalence of poverty, smoking, and comorbid medical conditions. While our findings may not be directly applicable to other hospitals with different patient demographics, the conditions that likely contribute to the high prevalence of airway obstruction in our patients are present throughout the United States and the world.

In conclusion, we found a high prevalence of airway obstruction in an inner-city teaching hospital. The admission history, medications, and discharge summary were not sensitive for detecting airway obstruction or diagnosing OLD. Our study suggests that routine spirometry in hospitalized patients, particularly in those > 45 years old may be useful to identify patients with airway obstruction and possibly to initiate counseling or appropriate medical treatment.


   Appendix
TOP
 Abstract
 Introduction
 Materials and Methods
 Results
 Discussion
 Appendix
References
 
Members of the Longcope Spirometry Investigation Team include Hossein Ardehali, MD, PhD; Marcus Brown, MD; Hetty Carraway, MD; Neil Evans, MD; Stuart Levine, MD; Susan Mani, MD; Jennifer Myers, MD; and David Zaas, MD.


   Footnotes
 
Abbreviations: ATS = American Thoracic Society; GOLD = Global Initiative for Chronic Obstructive Lung Disease; OLD = obstructive lung disease

Received for publication March 31, 2003. Accepted for publication July 16, 2003.


   References
TOP
 Abstract
 Introduction
 Materials and Methods
 Results
 Discussion
 Appendix
 References
 

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