1. Use of exercise tests in primary care: importance for referral decisions and possible bias in the decision process; a prospective observational study
Gunnar Nilsson1, 2; Thomas Mooe1; Lars Söderström2; Eva Samuelsson1
1. Department of Public Health and Clinical
Medicine, Umeå University, Umeå, Sweden;
2. Unit of Research, Education and
Development – Östersund Hospital,
Östersund, Sweden.
Aim: We evaluated the results of exercise tests for selection of patients to cardiologic care, and if referral decisions were biased by sex, socioeconomy or age.
Methods : Primary care patients, 438 men and 427 women, with exercise testing for suspected coronary disease. Referrals to cardiologist were registered within six months from exercise testing. Predictive variables were identified by multivariable logistic regression. Socioeconomy was assessed by education and employment grade.

2. Results
Patients with positive, non conclusive or negative exercise tests were referred to cardiologist in 67.3%, 26.1% and 3.5%, respectively.
Overall, there was no significant difference in referral rates, related to gender or socio-economic level.
Self employment predicted referral in women.
Among non-manual employees, male patients were referred more frequently.
Positive/non conclusive exercise tests and exertional chest pain predicted referral in both sexes.
In patients with a positive exercise test, referral rates decreased with age, adjusted for previous revascularization, myocardial infarction, transitory ischaemic attack, stroke or exertional chest pain (OR 0.48, 95% CI ; p=0.042).
Cardiovascular events occurred in 22.2% of non-referred patients with a positive exercise test.
These patients were not considered for cardiologic care in 56% of cases.

3. Table 1 Adjusted ORs for referral to cardiologist according to patient characteristics in women and menmen
Women (n=427)
Men (n=438)
OR (95% CI) P
Positive/inconclusive exercise test
11.07 ( )
<0.001
13.60 ( )
Exertional chest pain
2.40 ( )
0.043
3.22 ( )
0.002
Pathologic ST-T segment on resting ECG - NS
2.42 ( )
0.034
Previous revascularisation
5.15 ( )
0.018
Self-employed
3.92 ( )
0.016
Age
0.99 ( )
0.589
1.01 ( )
0.655
Characteristics remaining significant in a multivariable analysis adjusted for age. Follow-up within six months of exercise testing. NS=not significant.

4. Employment Employed Self-employed Female Male
Table 2 Adjusted ORs (95% CIs) for referral to cardiologic evaluation, by sex and employment
Employment
Employed
Self-employed
Female
1.00
(n=352)
3.62 ( )
(n=32)
Male
1.73 ( )
(n=332)
1.87 ( )
(n=77)
Referrals took place within six months from exercise testing. Employed females served as reference. ORs were adjusted for age, exertional chest pain, and positive/inconclusive exercise test result versus negative test.

5. Conclusion & Clinical Relevance
Table 3 Patients with positive exercise tests, by age and referral to cardiologic evaluation within six months
Age in years
Exercise test positive
Referred to cardiologist (%)
Not referred to cardiologist (%)
40-49
4 (100%)
0 (0%)
50-59
5 (83.3%)
1 (16.7%)
60-69
14 (73.7%)
5 (26.3%)
70-79
12 (57.1%)
9 (42.9%)
80-89
2 (40%)
3 (60%)
All ages
37 (67.3%)
18 (32.7%)
Fifty-five primary care patients with positive exercise tests, of 865 patients examined; two-sided test for trend, p=0.024.
Gender and socio-economy interactions affected the referral rates, after exercise testing.
In patients with a positive exercise test, referral rates decreased with age.
Exercise tests are important to select patients to cardiologic care.
An increased awareness of possible bias regarding age, gender and socioeconomy is necessary.

6. Table 3 Patients with positive exercise tests, by age and referral to cardiologic evaluation within six months
Age in years
Exercise test positive
Referred to cardiologist (%)
Not referred to cardiologist (%)
40-49
4 (100%)
0 (0%)
50-59
5 (83.3%)
1 (16.7%)
60-69
14 (73.7%)
5 (26.3%)
70-79
12 (57.1%)
9 (42.9%)
80-89
2 (40%)
3 (60%)
All ages
37 (67.3%)
18 (32.7%)
Fifty-five primary care patients with positive exercise tests, of 865 patients examined; two-sided test for trend, p=0.024.

7. Conclusion & Clinical Relevance
Gender and socio-economy interactions affected the referral rates, after exercise testing.
In patients with a positive exercise test, referral rates decreased with age.
Exercise tests are important to select patients to cardiologic care.
An increased awareness of possible bias regarding age, gender and socioeconomy is necessary.