Table 1.
Baseline Characteristics of the Study Population Stratified by Immediate or Delayed Antibiotic Prescribing (in CPRD and SAIL)
| CPRD | SAIL | |||
|---|---|---|---|---|
| Immediate Antibiotic (n = 2 185 492) | Delayed Antibiotic (n = 197 522) | Immediate Antibiotic (n = 624 483) | Delayed Antibiotic (n = 63 287) | |
| Time, mean (SD) from antibiotic prescription until censoring, years | 5.5 (3.7) | 5.3 (3.7) | 5.1 (4.0) | 5.0 (4.1) |
| Age, mean (SD), years | 36.9 (24.6) | 31.7 (26.6) | 28.5 (24.3) | 22.1 (25.0) |
| Age, n (%) | ||||
| 0–17 years | 623 552 (28.5) | 80 342 (40.7) | 267 056 (42.8) | 36 998 (58.5) |
| 18–59 years | 1 080 113 (49.4) | 78 464 (39.7) | 266 614 (42.7) | 18 756 (29.6) |
| ≥60 years | 481 827 (22.0) | 38 716 (19.6) | 90 813 (14.5) | 7533 (11.9) |
| Women, n (%) | 1 251 759 (57.3) | 115 439 (58.4) | 347 963 (55.7) | 35 270 (55.7) |
| Indication, n (%) | ||||
| URTI | 481 313 (22.0) | 76 365 (38.7) | 124 870 (20.0) | 27 631 (43.7) |
| Cough /cold | 907 769 (41.5) | 114 000 (57.7) | 235 066 (37.6) | 34 029 (53.8) |
| Sore throat | 819 195 (37.5) | 60 490 (30.6) | 270 473 (43.3) | 18 446 (29.1) |
| Charlson comorbidity index, n (%) | ||||
| No (score 0) | 1 504 443 (68.8) | 141 461 (71.6) | 596 526 (95.5) | 60 970 (96.3) |
| Low (1–2) | 565 661 (25.9) | 46 273 (23.4) | 23 026 (3.7) | 1907 (3) |
| Moderate (3–4) | 88 553 (4.1) | 7515 (3.8) | 3755 (0.6) | 318 (0.5) |
| High (5–6) | 19 789 (0.9) | 1704 (0.9) | 1058 (0.2) | 81 (0.1) |
| Very high (≥7) | 7046 (0.3) | 569 (0.3) | 118 (0) | 11 (0%) |
| Flu vaccination year before, n (%) | 489 251 (22.4) | 43 392 (22.0) | 104 514 (16.7) | 10 421 (16.5) |
| Hospital admission year before, n (%) | 35 936 (1.6) | 4007 (2.0) | 10 426 (1.7) | 1411 (2.2) |
| Calendar year, n (%) | ||||
| 2000–2004 | 589 076 (27.0) | 49 742 (25.2) | 86 702 (13.9) | 7604 (12.0) |
| 2005–2009 | 883 375 (40.4) | 79 254 (40.1) | 176 492 (28.3) | 16 751 (26.5) |
| 2010–2015 | 713 041 (32.6) | 68 526 (34.7) | 361 289 (57.9) | 38 932 (61.5) |
Characteristics at each antibiotic prescription are shown.
Abbreviations: CPRD, Clinical Practice Research Datalink; SAIL, Secure Anonymized Information Linkage; URTI, upper respiratory tract infection.