TABLE 4.
30-day Risk Difference Estimates of Antibiotic Prescription Switch versus Nitrofurantoin Initiators by Index Antibiotic Agent, Overall and by Subgroup (Intention-to-treat Analyses)
| Risk Difference, % (95% CI) versus Nitrofurantoina | |||||
|---|---|---|---|---|---|
|
| |||||
| First-line agents | Non-first-line Agents | Non-recommended agents | |||
|
| |||||
| TMP/SMX | Fluoroquinolone | Broad-spectrum β-lactam | Narrow-spectrum β-lactam | AMX/AMP | |
| Overall analyses | |||||
| Crude | 1.2 (1.0–1.3) | −4.4 (−4.6−−4.3) | −1.0 (−1.5−−0.4) | −0.7 (−1.1−−0.3) | 3.7 (2.8–4.6) |
| Weighted | 1.6 (1.3–1.7) | −4.4 (−4.5−−4.2) | −0.7 (−1.4–0.1) | −0.3 (−0.8–0.2) | 3.6 (2.5–4.6) |
| Subgroup analyses (weighted) | |||||
| Age group, y | |||||
| 18–24 | 1.1 (0.8–1.5) | −4.4 (−4.7−−4.1) | −1.4 (−3.2–0.4) | −1.2 (−1.9−−0.3) | 1.9 (0.0–3.6) |
| 25–29 | 2.6 (2.1–3.1) | −3.5 (−3.9−−3.2) | 0.2 (−1.8–2.0) | 0.3 (−0.9–1.5) | 6.3 (3.8–9.0) |
| 30–34 | 2.1 (1.6–2.6) | −4.0 (−4.4−−3.6) | 0.3 (−1.5–2.2) | 1.0 (−0.3–2.1) | 5.6 (3.1–8.4) |
| 35–39 | 1.3 (0.9–1.8) | −4.6 (−4.9−−4.2) | −0.1 (−2.0–1.8) | −1.1 (−2.3–0.2) | 2.9 (0.6–5.0) |
| 40–44 | 1.0 (0.5–1.5) | −5.4 (−5.8−−5.0) | −0.6 (−2.3–1.4) | 0.6 (−0.7–1.9) | 2.8 (−0.2–5.4) |
| Year | |||||
| 2006–2008 | 1.0 (0.6–1.4) | −5.1 (−5.4−−4.8) | −1.1 (−2.5–0.7) | 0.3 (−0.8–1.4) | 4.5 (2.3–6.5) |
| 2009–2011 | 1.7 (1.4–2.0) | −4.2 (−4.5−−4.0) | 0.5 (−0.9–2.0) | −0.1 (−0.9–0.9) | 2.7 (1.1–4.4) |
| 2012–2015 | 1.6 (1.4–2.0) | −4.2 (−4.5−−3.9) | −1.8 (−2.8−−0.7) | −0.6 (−1.3–0.1) | 3.8 (2.3–5.5) |
| Region of residence | |||||
| Northeast | 1.5 (1.0–2.1) | −4.2 (−4.7−−3.8) | −1.5 (−3.3–0.4) | 0.9 (−0.8–2.7) | 6.1 (3.5–9.4) |
| Midwest | 1.1 (0.8–1.5) | −4.5 (−4.8−−4.1) | 0.4 (−1.3–2.4) | −0.4 (−1.3–0.5) | 4.7 (2.6–6.7) |
| South | 1.4 (1.1–1.7) | −4.4 (−4.6−−4.2) | −1.6 (−2.5−−0.6) | −0.5 (−1.3–0.2) | 2.4 (0.8–3.8) |
| West | 2.2 (1.8–2.6) | −4.3 (−4.7−−4.0) | 0.8 (−1.2–2.8) | −0.4 (−1.1–0.4) | 3.4 (1.1–5.7) |
| Initial laboratory testingc | |||||
| None | 0.9 (0.5–1.4) | −3.9 (−4.4−−3.6) | −2.0 (−3.5−−0.5) | −0.1 (−1.1–1.0) | 1.2 (−1.1–3.6) |
| Urinalysis only | 1.0 (0.7–1.3) | −3.8 (−4.0−−3.5) | −0.5 (−1.7–0.8) | −0.8 (−1.5−−0.2) | 1.2 (−0.2–2.6) |
| Culture ± urinalysis | 2.1 (1.8–2.3) | −4.9 (−5.1−−4.7) | −0.4 (−1.4–0.7) | 0.3 (−0.5–1.0) | 5.5 (4.0–7.3) |
| No culture | 1.0 (0.7–1.2) | −3.8 (−4.0−−3.6) | −1.0 (−2.0–0.1) | −0.6 (−1.2–0.0) | 1.5 (0.2–2.7) |
Abbreviations: AMX/AMP indicates amoxicillin or ampicillin; CI, confidence interval; PS, propensity score, TMP/SMX, trimethoprim-sulfamethoxazole.
Propensity score (PS) weighting was implemented by standardized mortality ratio weighting where patients were weighted to reflect the covariate distributions in the nitrofurantoin treatment group. The nitrofurantoin cohort was given a weight of 1 and each comparator PS/(1 – PS), in which PS is the propensity score of nitrofurantoin initiators in the study population. The PS models were estimated using the following covariates: age, month, year, geographic region, provider type, drug or alcohol abuse, deficiency anemias, chronic pulmonary disease, depression, psychoses, hypertension, obesity, initial receipt of urinalysis, and initial receipt of urine culture.
Sample size of the subgroups for the pyelonephritis analysis: none (n=163,184), urinalysis only (n=425,718), culture ± urinalysis (n=545,772), and no culture (n=588,902).
Sample size of the subgroups for the prescription switch analysis: none (n=164,088), urinalysis only (n=427,793), culture ± urinalysis (n=548,830), and no culture (n=591,881).