Primary analysis: multivariable analysis of the association between RTI-associated antibiotic exposure in the previous year and subsequent response failure for acute RTI, N = 1377 response failures
| Variable | Adjusted odds ratio (95% CI) | P-value |
|---|---|---|
| Number of RTI antibiotic courses in previous year | ||
| None, n= 1050 | 1 (reference) | |
| 1 antibiotic, n= 230 | 1.03 (0.88 to1.21) | 0.67 |
| ≥2 antibiotics, n= 97 | 1.32 (1.04 to 1.66) | 0.02 |
| Age at index prescription (T0) (years) | 0.95 (0.90 to 0.99) | 0.018 |
| Sex | ||
| Male | 1 (reference) | |
| Female | 0.85 (0.76 to 0.95) | 0.003 |
| Seasona | ||
| Winter | 1 (reference) | |
| Spring | 1.09 (0.96 to 1.26) | 0.18 |
| Summer | 1.22 (1.03 to 1.43) | 0.02 |
| Autumn | 1.00 (0.87 to 1.16) | 0.99 |
| RTI typeb | ||
| URTI | 1 (reference) | |
| LRTI | 0.88 (0.75 to 1.04) | 0.13 |
| AOM | 1.05 (0.88 to 1.25) | 0.60 |
| URTI and LRTI | 2.37 (1.48 to 3.79) | <0.001 |
| Other mix | 0.84 (0.31 to 2.27) | 0.73 |
| Comorbidity | ||
| None | 1 (reference) | |
| Present | 1.20 (0.98 to 1.48) | 0.08 |
| Antibiotic drug class | ||
| Cephalosporin | 1 (reference) | |
| Macrolides | 0.77 (0.50 to 1.19) | 0.25 |
| Broad-spectrum penicillin (amoxicillin, co-amoxiclav) | 0.47 (0.30 to 0.71) | 0.001 |
| Penicillinase-resistant (flucloxacillin) | 0.46 (0.14 to 1.54) | 0.21 |
| Penicillin V (phenoxymethylpenicillin) | 0.60 (0.39 to 0.94) | 0.03 |
| Quinolones | 0 (empty) | |
| Trimethoprim-cotrimoxazole | 1.01 (0.41 to 2.53) | 0.98 |
| Number of response failures in previous year | ||
| None | 1 (reference) | |
| 1 | 2.08 (1.67 to 2.58) | <0.001 |
| 2 | 3.93 (1.18 to 13.12) | 0.03 |
| Number of acute RTI consultations in previous year | 1.03 (1.02 to 1.05) | <0.001 |
| Social deprivation | ||
| 1 (least deprived) | 1 (reference) | |
| 2 | 0.96 (0.81 to 1.13) | 0.61 |
| 3 | 1.08 (0.92 to 1.28) | 0.34 |
| 4 | 1.12 (0.95 to 1.32) | 0.17 |
| 5 (most deprived) | 0.99 (0.84 to 1.18) | 0.96 |
| Vaccination status at index prescription (T0) | ||
| Incomplete or none | 1 (reference) | |
| Complete | 1.41 (1.26 to 1.59) | <0.001 |
↵a Seasons: winter (December to February); spring (March to May); summer (June to August); autumn (September to November).
↵b URTI: acute sinusitis, sore throat, laryngitis, coughs, for example, LRTI: pneumonia, bronchitis, for example. URTI and LRTI: two separate RTI Read codes for antibiotic prescribing event on same day. AOM = acute otitis media. IQR = interquartile range. LRTI = lower respiratory tract infection. RTI = respiratory tract infection. URTI = upper respiratory tract infection.