Objectives
The renin-angiotensin system contributes to the pathogenesis of abdominal aortic aneurysms (AAA). The pulmonary system regulates circulating angiotensin II and 1-7 via angiotensin-converting enzyme and angiotensin-converting enzyme 2 activity. Pulmonary diseases, including chronic obstructive pulmonary disease and sleep apnea are associated with increased AAA risk. This study examined whether a similar association exists with influenza pneumonia (IP).
Methods
Using a cohort discovery tool with institutional review board approval for informed consent waived, electronic health records from Stanford health system were retrospectively queried to identify patients aged 50 years or more with a history of IP or noninfluenza pneumonia (NIP). After controlling for gender, race, and cigarette smoking, AAA prevalence and odds ratios were calculated for patients with IP or NIP as a function of age and diabetes status.
Results
We identified 935 and 6145 AAA patients in the IP (45,110) and NIP (1,993,760) cohorts, respectively. IP was associated with increased AAA prevalence regardless of sex, age, smoking, diabetic status or racial classification (excepting Native Americans) (Table I). After controlling for White race and male sex, AAA prevalence remained higher in IP smoking patients in most age groups regardless of diabetic status. OR for IP-associated AAA risk ranged from 1.48 to 2.31 (Table II). In White male nonsmokers, AAA prevalence was also higher in IP than NIP patients, particularly in nondiabetics (odds ratio, 10.10-228.86) (Table III).
Conclusions
This study suggests that influenza pneumonia is positively associated with AAA disease prevalence in older patients. Additional study is needed to determine whether this association is causal and, ultimately, whether AAA screening and surveillance protocols should be adjusted accordingly.
Table IAbdominal aortic aneurysm (AAA) prevalence in two patient cohorts by sex, age, race, smoking status, and diabetes
| Variable | Patients with NIP | Patients with IP | ||||
|---|---|---|---|---|---|---|
| Total | AAA | Prevalence | Total | AAA | Prevalence | |
| Sex | ||||||
| Male | 928,025 | 4600 | 4.9 | 22,215 | 710 | 31.9* |
| Female | 1,055,580 | 1545 | 1.5 | 22,885 | 225 | 9.8* |
| Age, years | ||||||
| 50-59 | 578,245 | 295 | 0.5 | 3530 | 15 | 4.2* |
| 60-69 | 535,705 | 860 | 1.6 | 8835 | 120 | 13.6* |
| 70-79 | 402,250 | 1945 | 4.8 | 10,985 | 230 | 20.9* |
| 80-89 | 227,350 | 1850 | 8.1 | 9075 | 270 | 29.8* |
| 90- | 250,210 | 1190 | 4.8 | 12,675 | 295 | 23.3* |
| Race | ||||||
| Amerind | 4505 | 15 | 3.3 | 120 | 0 | 0.0 |
| Asian | 149,855 | 725 | 4.8 | 5195 | 95 | 18.3* |
| Black | 61,915 | 250 | 4.0 | 2260 | 35 | 15.5* |
| White | 803,570 | 4175 | 5.2 | 27,935 | 680 | 24.3* |
| Other | 186,195 | 575 | 3.1 | 5010 | 85 | 16.9* |
| Unknown | 780,750 | 355 | 0.5 | 4080 | 20 | 4.9* |
| Smoking | ||||||
| Yes | 516,360 | 5065 | 9.8 | 31,780 | 850 | 26.7* |
| No | 1,477,400 | 1075 | 7.3 | 13,325 | 85 | 6.4* |
| Diabetes | ||||||
| Yes | 106,100 | 1295 | 12.2 | 10,945 | 345 | 31.5* |
| No | 1,893,285 | 4730 | 2.5 | 34,160 | 585 | 17.1* |
IP, Influenza pneumonia; NIP, noninfluenza pneumonia.
Prevalence: AAA patients per 1000 IP or NIP patients.
*χ2 test; P < .01 compared with NIP patients.
Table IIAbdominal aortic aneurysm (AAA) prevalence and odds ratios by age in white male smoker patients after stratified by diabetic status
| Diabetes | Patients with NIP | Patients IP | Odds ratio (95% confidence interval) | ||||
|---|---|---|---|---|---|---|---|
| Total | AAA | Prevalence | Total | AAA | Prevalence | ||
| Yes (age) | |||||||
| 50-59 | 2465 | 10 | 4.1 | 145 | 0 | 0.0 | - |
| 60-69 | 5860 | 90 | 15.4 | 575 | 20 | 34.8 | 2.31 (1.34-3.82)* |
| 70-79 | 6855 | 220 | 32.1 | 880 | 55 | 62.3 | 2.01 (1.45-2.74)* |
| 80-89 | 3775 | 200 | 52.9 | 715 | 60 | 83.9 | 1.64 (1.19-2.22)* |
| 90- | 1275 | 75 | 58.8 | 450 | 30 | 66.7 | 1.14 (0.71-1.79) |
| No (age) | |||||||
| 50-59 | 21,615 | 60 | 2.8 | 620 | 0 | 0.0 | - |
| 60-69 | 34,015 | 285 | 8.4 | 1580 | 30 | 18.9 | 2.29 (1.51-3.56)* |
| 70-79 | 29,940 | 745 | 24.9 | 1910 | 80 | 41.9 | 1.71 (1.34-2.17)* |
| 80-89 | 14,535 | 615 | 42.3 | 1380 | 85 | 61.6 | 1.49 (1.16-1.88)* |
| 90- | 6355 | 320 | 50.4 | 1440 | 105 | 72.9 | 1.48 (1.17-1.87)* |
IP, Influenza pneumonia; NIP, noninfluenza pneumonia.
Age: years. Prevalence: AAA patients per 1000 patients with IP or NIP.
*χ2 test; P < .01.
Table IIIAbdominal aortic aneurysm (AAA) prevalence and odds ratios by age in white male n on smoker patients after stratified by diabetic status
| Diabetes | Patients with NIP | Patients with IP | Odds ratio (95% confidence interval) | ||||
|---|---|---|---|---|---|---|---|
| Total | AAA | Prevalence | Total | AAA | Prevalence | ||
| Yes (age) | |||||||
| 50-59 | 1379 | 0 | 0 | 5 | 0 | 0 | – |
| 60-69 | 1305 | 0 | 0 | 40 | 0 | 0 | – |
| 70-79 | 1365 | 5 | 3.7 | 80 | 0 | 0 | – |
| 80-89 | 825 | 20 | 24.2 | 60 | 5 | 83.3 | 3 66 (1.03-10.54)* |
| 90- | 495 | 15 | 30.3 | 90 | 10 | 111.1 | 4.00 (1.54-9.87)* |
| No (age) | |||||||
| 50-59 | 70,250 | 35 | 0.5 | 55 | 5 | 90.9 | 20.60 (6.04-58.84)* |
| 60-69 | 61,555 | 50 | 0.8 | 255 | 40 | 156.8 | 228.86 (143.62-361.63)* |
| 70-79 | 46,675 | 100 | 2.1 | 665 | 85 | 127.8 | 68 26 (49.88-93.14)* |
| 80-89 | 28,380 | 130 | 4.5 | 725 | 55 | 75.9 | 17.84 (12.65-24.88)* |
| 90- | 39,685 | 155 | 3.9 | 2100 | 80 | 38.1 | 10.10 (7.59-13.37)* |
IP, influenza pneumonia; NIP, noninfluenza pneumonia.
Age: years. Prevalence: AAA patients per 1000 patients with IP or NIP.
*χ2 test; P < .01.
Article info
Publication history
Published online: June 10, 2022
22-VIRC-452-AHA-VDFootnotes
Author Disclosures: B. Xu: Nothing to disclose; R. L. Dalman: Nothing to disclose
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