Figure 1
Influenza Infection Timeline. Influenza risk interval is defined as the 7 days after laboratory confirmed influenza. Influenza control interval is defined as the 365 days or 52 weeks before and 358 days or 51 weeks after the risk interval.
Figure 2
Flow of Study Participants. Influenza positive patients stratified based on their heart failure hospitalization (HFH) during the influenza risk interval compared to the control interval.
Table 1
Baseline Characteristics.
| TOTAL N = 114 | RISK INTERVAL N = 28 | CONTROL INTERVAL N = 86 | P-VALUE | |
|---|---|---|---|---|
| Gender, n (%) | 0.16 | |||
| Male | 66 (57.9) | 13 (46.4) | 53 (61.6) | |
| Female | 48 (42.1) | 15 (53.6) | 33 (38.4) | |
| Coronary Artery Disease, n (%) | 0.51 | |||
| No | 79 (69.3) | 18 (64.3) | 61 (70.9) | |
| Yes | 35 (30.7) | 10 (35.7) | 25 (29.1) | |
| Hypertension, n (%) | 0.14 | |||
| No | 22 (19.3) | 3 (10.7) | 19 (22.1) | |
| Yes | 92 (81.7) | 25 (89.3) | 67 (77.9) | |
| Diabetes, n (%) | 0.28 | |||
| No | 63 (55.3) | 13 (46.4) | 50 (58.1) | |
| Yes | 51 (44.7) | 15 (53.6) | 36 (41.9) | |
| Dyslipidemia, n (%) | 0.26 | |||
| No | 90 (78.9) | 20 (71.4) | 70 (81.4) | |
| Yes | 24 (21.1) | 8 (28.6) | 16 (18.6) | |
| Cerebrovascular Disease, n (%) | 0.12 | |||
| No | 96 (84.2) | 26 (92.9) | 70 (81.4) | |
| Yes | 18 (15.8) | 2 (7.1) | 16 (18.6) | |
| Smoking, n (%) | 0.42 | |||
| No | 84 (73.7) | 19 (67.9) | 65 (75.6) | |
| Yes | 30 (26.3) | 9 (32.1) | 21 (24.4) | |
| Peripheral Vascular Disease, n (%) | 0.61 | |||
| No | 105 (92.1) | 26 (92.9) | 79 (91.9) | |
| Yes | 9 (7.9) | 2 (7.1) | 7 (8.1) | |
| Mean BMI (kg/m²) ± SD | 29.82 ± 9.2 | 27.74 ± 8.2 | 30.35 ± 9.5 | 0.35 |
| Mean EF (%) ± SD | 46.1 ± 14.5 | 47.2 ± 13.9 | 45.6 ± 14.9 | 0.72 |
| Median BNP (pg/mL) (IQR) | 700.50 (922) | 729.69 (1135) | 657 (773) | 0.58 |
Table 2
Incidence Rate and Ratio Sample Calculation.
| INFLUENZA TIME INTERVAL | INCIDENCE RATE | INCIDENCE RATIO |
|---|---|---|
| Risk Interval | ||
| Control Interval |
Figure 3
Incidence Ratios for Heart Failure Hospitalization According to the Days Following Laboratory-Confirmed Influenza Infection.
Table 3
Subgroup Analyses Comparing Incidence Ratios for Heart Failure Hospitalization after Laboratory-Confirmed Influenza Infection.
| SUBGROUP | INCIDENCE RATIO (95% CONFIDENCE INTERVAL) | P-VALUE FOR INTERACTION |
|---|---|---|
| Age | 0.23 | |
| ≤65 years | 55.46 (22.13–139.01) | |
| >65 years | 29.63 (18.24–48.14) | |
| Gender | 0.16 | |
| Male | 25.26 (13.77–46.33) | |
| Female | 46.82 (25.43–86.19) | |
| Influenza Type | 0.17 | |
| Influenza A | 29.23 (18.0–47.46) | |
| Influenza B | 60.08 (23.65–152.60) | |
| Coronary Artery Disease | 0.51 | |
| Yes | 41.2 (19.79–85.78) | |
| No | 30.39 (17.96–51.41) | |
| Diabetes | 0.28 | |
| Yes | 42.92 (23.49–78.39) | |
| No | 26.78 (14.55–49.29) |