Comparison of patients infected with NAP1 versus non-NAP1 strains, by demographic and clinical characteristics, and severe outcomes*
| Variable | Strain; no. (%) of patients†‡ | p value¶ | ||
|---|---|---|---|---|
| All strains n = 2690 | NAP1 n = 1011 | Non-NAP1§ n = 1679 | ||
| Sex, female | 1351 (50.4) | 502 (49.9) | 849 (50.8) | 0.6 |
| Age, yr, mean ± SD | 70.1 ± 17.1 | 74.0 ± 14.8 | 67.8 ± 17.9 | < 0.001 |
| Age group, yr | ||||
| 18–64 | 870 (32.3) | 241 (23.8) | 629 (37.5) | < 0.001 |
| ≥ 65 | 1818 (67.6) | 769 (76.1) | 1049 (62.5) | < 0.001 |
| Unknown | 2 (0.1) | 1 (0.1) | 1 (0.1) | Not tested |
| Laboratory results | ||||
| Temperature, °C, mean ± SD | 37.1 ± 0.8 | 37.1 ± 0.7 | 37.1 ± 0.8 | 0.9 |
| Leukocyte count, ×109/L, median (IQR) | 11.6 (7.8–16.9) | 13.0 (8.9–19.1) | 10.8 (7.2–15.9) | < 0.001 |
| Albumin, g/L, median (IQR) | 26.0 (21.3–30.0) | 26.0 (21.0–30.0) | 26.0 (22.0–31.0) | 0.6 |
| ICU admission | ||||
| All-cause | 142 (5.4) | 58 (5.8) | 84 (5.1) | 0.5 |
| Complication from C. difficile infection | 43 (1.6) | 27 (2.7) | 16 (1.0) | 0.001 |
| Colectomy | 34 (1.3) | 18 (1.8) | 16 (1.0) | 0.07 |
| Outcome | ||||
| Discharged or transferred | 1550 (59.2) | 552 (55.5) | 998 (61.5) | 0.002 |
| Remained in hospital | 723 (27.6) | 286 (28.1) | 437 (26.9) | 0.3 |
| All-cause death, age, yr | 327 (12.5) | 155 (15.6) | 172 (10.6) | < 0.001 |
| 18–64 | 51 (6.1) | 17 (7.2) | 34 (5.7) | 0.4 |
| 65–74 | 60 (11.5) | 22 (12.5) | 38 (10.9) | 0.6 |
| 75–84 | 103 (15.5) | 59 (19.3) | 44 (12.3) | 0.01 |
| ≥ 85 | 113 (19.7) | 57 (20.8) | 56 (18.7) | 0.5 |
| Death attributable to C. difficile infection, age, yr | 113 (4.3) | 66 (6.6) | 47 (2.9) | < 0.001 |
| 18–64 | 17 (2.0) | 9 (3.8) | 8 (1.3) | 0.04 |
| 65–74 | 14 (2.7) | 8 (4.5) | 6 (1.7) | 0.08 |
| 75–84 | 30 (4.5) | 25 (12.2) | 5 (1.4) | < 0.001 |
| ≥ 85 | 52 (9.6) | 24 (8.8) | 28 (9.3) | 0.8 |
| Unknown | 17 (0.7) | 2 (0.2) | 15 (0.9) | Not tested |
Note: ICU = intensive care unit, IQR = interquartile range; SD = standard deviation.
↵* All patients include cases from targeted surveillance month of March and April from each year where more detailed questions and stool samples were collected.
↵† Unless stated otherwise.
↵‡ Not all subgroup values total the population size because of missing data; percentages are calculated on the basis of available data.
↵§ Non-NAP1 (all other strains) including NAP2, NAP3, NAP5, NAP6, NAP7, NAP8, NAP9, NAP10, NAP11, NAP12 and unassigned.
↵¶ p values are for comparisons between groups with NAP1 and non-NAP1 strains.