Table 1:

Baseline characteristics of patients with relatively low estimated glomerular filtration rate

CharacteristicDrug; no. (%) of patients*Standardized difference relative to nitrofurantoin, %
Nitrofurantoin n = 3739Ciprofloxacin n =1989Norfloxacin n = 2032TMP–SMX n = 1463CiprofloxacinNorfloxacinTMP– SMX
Age, yr, mean ± SD78 ± 779 ± 779 ± 778 ± 7381
Year of cohort entry
 2002–2005609 (16.3)310 (15.6)610 (30.0)386 (26.4)23325
 2006–20091414 (37.8)771 (38.8)828 (40.7)539 (36.8)262
 2010–20131716 (45.9)908 (45.6)594 (29.2)538 (36.8)03519
Rural residence367 (9.8)183 (9.2)232 (11.4)221 (15.1)2516
Prescription supply of 3–7 d2999 (80.2)1483 (74.6)1610 (79.2)1130 (77.2)1427
Health care use, mean ± SD§
 Primary care visits12.59 ± 10.6913.82 ± 11.8613.58 ± 11.9812.67 ± 10.801191
 Emergency department visits4.66 ± 4.664.65 ± 4.824.63 ± 4.394.90 ± 4.59015
 Hospital discharges2.55 ± 2.142.55 ± 2.102.84 ± 2.462.79 ± 2.2901311
 Urine cultures8.10 ± 6.719.18 ± 8.249.07 ± 8.918.04 ± 7.4014121
Prior antibiotic prescriptions
 0295 (7.9)137 (6.9)129 (6.4)133 (9.1)464
 1 or 2803 (21.5)372 (18.7)397 (19.5)310 (21.2)751
 3 or 4722 (19.3)362 (18.2)405 (19.9)273 (18.7)322
 ≥ 51919 (51.3)1118 (56.2)1101 (54.2)747 (51.1)1061
Comorbidities**
 Coronary artery disease††1842 (49.3)1029 (51.7)1073 (52.8)742 (50.7)573
 Dementia549 (14.7)306 (15.4)279 (13.7)202 (13.8)233
 Diabetes mellitus‡‡1086 (29.0)617 (31.0)571 (28.1)416 (28.4)421
 Heart failure986 (26.4)606 (30.5)621 (30.6)412 (28.2)994
 Peripheral vascular disease106 (2.8)57 (2.9)85 (4.2)63 (4.3)078
 Stroke171 (4.6)108 (5.4)87 (4.3)87 (6.0)416
 Urinary incontinence§§153 (4.1)96 (4.8)98 (4.8)55 (3.8)442
Baseline medications¶¶
 No. of unique medications, mean ± SD8.31 ± 4.188.72 ± 4.258.13 ± 4.098.02 ± 4.251074
 ACE inhibitor1497 (40.0)768 (38.6)829 (40.8)595 (40.7)321
 ARB1015 (27.1)561 (28.2)522 (25.7)332 (22.7)2310
 β-Blockers1632 (43.6)912 (45.8)887 (43.6)627 (42.9)402
 Calcium-channel blocker1781 (47.6)952 (47.9)946 (46.6)676 (46.2)023
 Loop diuretic969 (25.9)600 (30.2)563 (27.7)382 (26.1)940
 Potassium-sparing diuretic334 (8.9)181 (9.1)202 (9.9)148 (10.1)134
 Thiazide diuretic896 (24.0)441 (22.2)488 (24.0)360 (24.6)402
Prescriber characteristics
 Sex, female1431 (38.3)597 (30.0)546 (26.9)478 (32.7)464
 Time since graduation, yr, mean ± SD23.75 ± 10.8526.01 ± 11.2327.65 ± 10.2622.85 ± 10.8820378
  • Note: ACE = angiotensin converting enzyme, ARB = angiotensin II receptor blocker, SD = standard deviation, TMP–SMX = trimethoprim–sulfamethoxazole.

  • * Unless otherwise indicated.

  • Standardized differences are less sensitive to sample size than traditional measures for testing hypotheses. They provide a measure of the difference between groups divided by the pooled SD, where a value greater than 10% is considered to represent a meaningful difference. (25)

  • Municipalities with population < 10 000 were considered to be rural.

  • § Health care use (except for primary care visits) was assessed as the mean number of visits by a patient in the preceding 5 years.

  • Primary care visits were assessed as the mean number of visits by a patient in the preceding year.

  • ** Comorbidities were assessed for the preceding 5 years.

  • †† Coronary artery disease includes undergoing coronary artery bypass graft surgery or percutaneous coronary intervention and diagnosis of angina.

  • ‡‡ Diabetes mellitus was assessed through use of oral hypoglycemic medications and insulin prescriptions in the preceding 120 days.

  • §§ Urinary incontinence was assessed through prescriptions for overactive bladder medication in the preceding 120 days.

  • ¶¶ Baseline medications were assessed for the preceding 120 days.