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1 Dept of Medicine, University of Ottawa, and, 2 Clinical Epidemiology Unit, Ottawa Health Research Institute, Ottawa, ON, Canada.
CORRESPONDENCE: R. E. Dales, Division of Respirology, The Ottawa Hospital (General Campus), 501 Smyth Road, Box 211, Ottawa, Ontario K1H 8L6, Canada. Fax: 1 6137396266. E-mail: rdales{at}ohri.ca
Keywords: Airflow obstruction, clinical practice, sex, spirometry, treatment
Received: November 23, 2005
Accepted April 26, 2006
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ABSTRACT |
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 TOP ABSTRACT METHODSStatistical analysisRESULTSDISCUSSIONACKNOWLEDGEMENTSREFERENCES |
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Patients aged 
35 yrs who had ever smoked were enrolled when they presented for any reason to one of eight rural primary-care practices. Respiratory symptom questionnaires and spirometry were administered. In total, 1,034 patients had acceptable and reproducible spirometry, of whom 550 (53%) were males and 484 (47%) were females.
Males smoked more than females (41.2 versus 29.2 pack-yrs) respectively, and were more likely to have a pre-bronchodilator forced expiratory volume in one second/forced vital capacity <0.70 at 22.4 versus 11.8%, respectively. However, more females than males reported breathlessness (51.0 versus 42.8%, respectively), a prior diagnosis compatible with airflow obstruction and taking respiratory medications (23.4 versus 14.9%, respectively).
In conclusion, the current results suggest that females are more likely than males to report breathlessness and be prescribed respiratory medications independent of differences in the severity of airflow obstruction.
The most common causes of airflow obstruction in primary-care practices are chronic obstructive lung disease (COPD), characterised by progressive, partially reversible airway obstruction, and asthma, characterised by variable airflow limitation 1, 2. Previous studies have shown that the clinical diagnosis of chronic bronchitis is made more commonly in females than males, and emphysema is more commonly diagnosed in males than females 3. Hypothetical case presentations to primary-care physicians reveal that, for the same clinical history, males were more likely to be diagnosed with COPD and females with asthma 4. Whether or not females are more susceptible to cigarette smoke than males is controversial. A recent study in a pulmonary clinic matched females to males on forced expiratory volume in one second (FEV1) per cent predicted 5. Compared with males, females were younger, smoked less, were more breathless and reported poorer quality of life scores. The present study explores differences in clinical expression of airway disease, diagnoses and management in a primary-care setting. The study group was not selected based on the presence or absence of respiratory symptoms or known lung disease.
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METHODS |
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TOPABSTRACTMETHODSStatistical analysisRESULTSDISCUSSIONACKNOWLEDGEMENTSREFERENCES |
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Subjects
Eligible subjects were all patients presenting to their primary-care practitioners for any reason, who were aged 35 yrs, and who had smoked 20 packets of cigarettes in their lifetime. The patients were given a brief questionnaire by the clinic receptionist to determine their age and smoking history, and were asked whether they would agree to participate. Patients who were eligible and agreed to participate were approached by the research assistant and signed informed consent forms. Patients who could not perform spirometry were excluded. The study was approved by the Ottawa Hospital Human Ethics Committee.
Baseline data collection
Interviewer-administered questionnaires included questions about smoking, respiratory symptoms and diagnosed respiratory illnesses, and were taken from the American Thoracic Society (ATS) Questionnaire 6, which has been standardised and tested for reliability.
Spirometry was performed in the primary-care practice building by trained research assistants using a Microlab 3500® (Micro Medical Ltd, Kent, UK). Testing was carried out with the subjects seated. A maximum forced exhalation was carried out for a minimum of 6 s. A minimum of three and a maximum of eight forced vital capacity (FVC) manoeuvres were performed to obtain at least three acceptable loops, two of which were reproducible within 200 mL. The reference values for FEV1 and FVC were those of Knudson et al. 7. Post-bronchodilator FEV1 was measured 20 min after 200 µg of salbutamol in those with an FEV1/FVC <70% pred or an FEV1 <80% pred. All spirometry tests were reviewed by an independent senior cardiopulmonary technologist and two respirologists to ensure acceptability.
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Statistical analysis |
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TOPABSTRACTMETHODSStatistical analysisRESULTSDISCUSSIONACKNOWLEDGEMENTSREFERENCES |
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RESULTS |
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TOPABSTRACTMETHODSStatistical analysisRESULTSDISCUSSIONACKNOWLEDGEMENTSREFERENCES |
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To determine the degree to which the study group was representative of all eligible subjects, the entire clinical population that visited the eight primary-care practices was surveyed for several days. Of the 1,800 subjects who were 100% sampled, 561 were 35 yrs of age and had ever smoked. Compared with all of those eligible (aged 35 yrs and had ever smoked), the group studied using spirometry differed as follows: 1) aged 2 yrs younger; 2) 1% more males; and 3) 1 yr extra smoking.
In the study group of 1,034, males were on average 5.5 yrs older and had smoked for 12 pack-yrs more than females (p<0.0001; table 1
). Females reported dyspnoea (p = 0.008) and wheeze (p = 0.031) more frequently. Based on responses to the ATS Questionnaire 6, females were twice as likely to have been diagnosed with asthma, 20 versus 10% (p<0.0001), respectively, and two-thirds more likely to have been diagnosed with chronic bronchitis, 19 versus 11% (p = 0.001), respectively. The prevalence of airflow obstruction was higher in males than females. This was statistically significant when defined by FEV1/FVC <70% pred, but not significant when defined by the LLN criteria. In total, 123 (22%) males and 57 (12%) females had an FEV1/FVC <70% pre-bronchodilator (p<0.0001). FEV1/FVC less than LLN was present in 76 (14%) males and 54 (11%) females (p = 0.20). Females were also almost twice as likely to report using respiratory medications, 23 versus 15% (p = 0.0005), respectively.
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). There were no significant sex differences in reported respiratory diseases and medications.
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). Females were twice as likely as males to be prescribed medications unless airway obstruction was severe. When severe, 70% of both males and females reported taking at least one respiratory medication.
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). No significant differences were found between the sexes.
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DISCUSSION |
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TOPABSTRACTMETHODSStatistical analysisRESULTSDISCUSSIONACKNOWLEDGEMENTSREFERENCES |
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There also appears to be a sex-bias in the diagnosis of chronic bronchitis, which may influence population health statistics for respiratory disease. The defining symptom of bronchitis is mucus hypersecretion from the chest and does not require airflow obstruction to be present 10. Although males generally reported more sputum production, consistent with this diagnosis, females in the present study were more likely to be labelled as having chronic bronchitis. American national population database studies have also reported a greater prevalence of chronic bronchitis in females compared with males 3. The current results suggest that this observed difference may not reflect differences in mucus hypersecretion, but rather a physician diagnostic bias.
It is not possible to determine if the prevalence of asthma was truly higher in the female study population or whether there was a reporting bias. Self-reported asthma and bronchial hyperresponsiveness are known to be more common in adult females than adult males 11, 12. Chapman et al. 13 reported that clinicians presented with hypothetical cases were more likely to diagnose asthma in females than males despite similar age, smoking histories and symptoms. The present results also suggest a sex-bias in diagnosing asthma. Females were twice as likely as males to be diagnosed with asthma although bronchodilator responsiveness did not differ between the two groups. Females have been reported to use primary-care services with greater frequency, but to receive fewer specialist referrals than males and to be less likely than males to be referred for invasive cardiac procedures 4, 14, 15. These findings raise the expectation that females may also be relatively under-treated for respiratory disease. The current authors found the opposite to be true. Females were more likely to be prescribed respiratory medications until severe obstruction was present (table 3
). Males may be relatively under-treated at milder stages of airflow obstruction.
The two different criteria used to define airflow obstruction affected males and females differently in the present study. The FEV1/FVC ratio decreases with age among healthy adults. Elderly people without respiratory disease may have a FEV1/FVC within the LLN defined by a healthy reference population, yet have a FEV1/FVC <70% pred. This scenario occurred more often in males than females in the present study because the mean age of males was 62 versus 56 yrs for females.
In conclusion, the current authors found that sex differences in symptom reporting, diagnoses and management of respiratory illness exist in primary-care practices. Physician awareness of this issue may help reduce this presumably unintentional bias. It may stem from a difference in the prevalence of breathlessness, a subjective indicator. Perhaps increased use of spirometry, an objective measure, would reduce the sex-related biases and improve diagnosis and management of airway diseases in the primary-care practice setting.
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ACKNOWLEDGEMENTS |
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TOPABSTRACTMETHODSStatistical analysisRESULTSDISCUSSIONACKNOWLEDGEMENTSREFERENCES |
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REFERENCES |
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TOPABSTRACTMETHODSStatistical analysisRESULTSDISCUSSIONACKNOWLEDGEMENTSREFERENCES |
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This article has been cited by other articles:
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  L. J. Greaves and L. A. Richardson Tobacco Use, Women, Gender, and Chronic Obstructive Pulmonary Disease: Are the Connections Being Adequately Made? Proceedings of the ATS, December 1, 2007; 4(8): 675 - 679. [Abstract] [Full Text] [PDF]
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P. G. Camp and S. M. Goring Gender and the Diagnosis, Management, and Surveillance of Chronic Obstructive Pulmonary Disease Proceedings of the ATS, December 1, 2007; 4(8): 686 - 691. [Abstract] [Full Text] [PDF]
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 M. T. Dransfield, G. R. Washko, M. G. Foreman, R. S. J. Estepar, J. Reilly, and W. C. Bailey Gender Differences in the Severity of CT Emphysema in COPD Chest, August 1, 2007; 132(2): 464 - 470. [Abstract] [Full Text] [PDF]
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