Table 5. Balancing achieved by different propensity score-based matching strategies for later generation fluoroquinolone use.
| Covariate | Later generation FQN | No later generation FQN | Before matching | Matching within studyes, without replacement* | Matching within studies, with replacement* | Matching across studies without replacement* | Matching across studies with replacement* | |||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Mean (sd) | Mean (sd) | Std dif # (%) | p-value+ | Std dif (%) | p-value+ | Std dif (%) | p-value | Std dif (%) | p-value+ | Std dif (%) | p-value+ | |
| Age | 37.71 (14.75) | 39.63 (13.53) | 4.79 | 0.0017* | 10.50 | 0.104 | 3.35 | 0.123 | 2.24 | 0.736 | 2.83 | 0.147 |
| Male gender | 0.59 (0.49) | 0.69 (0.46) | -20.7 | 0 | 3.20 | 0.6698 | 13.50 | <.0001 | -2.84 | 0.6949 | 3.46 | 0.0817 |
| Extensive disease | 0.8 (0.4) | 0.72 (0.45) | 18.2 | 0 | 1.76 | 0.7815 | 1.31 | 0.5529 | 0.00 | 1.0000 | -3.79 | 0.0480 |
| Prior TB | 0.53 (0.5) | 0.71 (0.45) | -38.4 | 0 | -1.52 | 0.7815 | 2.20 | 0.3508 | -8.49 | 0.2008 | 13.55 | <.0001 |
| Prior MDR-TB | 0.23 (0.42) | 0.07 (0.26) | 45.3 | 0 | 4.90 | 0.3173 | -0.99 | 0.6858 | -5.37 | 0.4054 | -11.14 | <.0001 |
| Known HIV co-infection | 0.02 (0.15) | 0.17 (0.38) | -51.5 | 0 | 6.18 | 0.1573 | 3.44 | 0.0578 | 22.64 | 0.0039 | 8.28 | <.0001 |
| No. drugs (intensive) | 5.73 (1.58) | 5.13 (1.36) | -14.37 | <0.0001 | 1.84 | 0.746 | 2.65 | 0.226 | -10.53 | <0.001 | 0.54 | 0.453 |
| Total therapy (months) | 26.07 (16.2) | 16.84 (6.94) | -26.2 | <0.0001 | -6.86 | 0.053 | -6.52 | <0.001 | -14.70 | 0.016 | -16.61 | <0.001 |
| Logit of predicted propensity score | 3.39 (1.48) | 2.86 (1.29) | -13.35 | <0.0001 | -26.53 | <0.001 | -17.44 | <0.001 | -12.79 | <0.001 | 0.13 | 0.14 |
*One to one matching.
# Std dif = standardized difference for unexposed relative to exposed. FQN = fluoroquinolone. The differences in characteristics between exposed and unexposed individuals receiving were tested for significance using a paired t-test for continuous variables and McNemar’s test for dichotomous variables [34]. MDR-TB = multi-drug resistant tuberculosis. TB = tuberculosis. HIV = human immunodeficiency virus.