Baseline characteristics of participants and covariate balancea
| Variable | Trial (n= 2061) | Observational study (n= 780) | Observational study before and after applying propensity score weights | |||||
|---|---|---|---|---|---|---|---|---|
| Amoxicillin | Placebo | Total | Amoxicillin | No antibiotics | Total | Standardised mean difference | Standardised mean difference | |
| Females | 624/1038 (60.1) | 600/1023 (58.7) | 1224/2061 (59.4) | 144/233 (61.8) | 336/546 (61.5) | 480/779 (61.6) | 0.008 | 0.045 |
| Age, years; mean (SD) | 48.6 (16.7) | 49.3 (16.4) | 49.0 (16.5) | 54.6 (15.7) | 48.6 (16.9) | 51.5 (17.1) | 0.383 | 0.022 |
| Non-smoker (past or present) | 477/1037 (46.0) | 483/1022 (47.3) | 960/2059 (46.6) | 148/233 (63.5) | 289/545 (53.0) | 437/778 (56.2) | 0.383 | 0.006 |
| Illness duration before index consultation, days; mean (SD) | 9.5 (8.0) | 9.3 (7.2) | 9.4 (7.6) | 9.1 (6.3) | 9.8 (7.8) | 9.5 (7.1) | 0.212 | 0.066 |
| Respiratory rate, breaths per minute; mean (SD) | 16.9 (3.3) | 16.9 (3.3) | 16.9 (3.3) | 17.9 (3.9) | 16.9 (4.2) | 17.1 (4.0) | 0.262 | −0.004 |
| Temperature, °C; mean (SD) | 36.7 (3.3) | 36.8 (3.3) | 36.8 (3.3) | 36.8 (0.6) | 36.7 (0.6) | 36.7 (0.6) | 0.145 | 0.001 |
| Lung diseaseb | 163/1037 (15.7) | 147/1023 (14.4) | 310/2060 (15.0) | 67/233 (28.8) | 86/545 (15.8) | 153/778 (19.7) | 0.320 | −0.034 |
| Mean severity score (all symptoms);c mean (SD) | 2.1 (0.5) | 2.1 (0.5) | 2.1 (0.5) | 2.3 (0.5) | 2.0 (0.5) | 2.1 (0.5) | 0.652 | −0.042 |
| Sputum production | 814/1036 (78.6) | 824/1021 (80.7) | 1638/2057 (79.6) | 205/233 (88.0) | 415/546 (76.0) | 620/779 (79.6) | 0.267 | −0.013 |
| Discoloured sputumd | 481/968 (49.7) | 468/957 (48.9) | 949/1922 (49.4) | 120/233 (51.5) | 250/547 (45.7) | 370/780 (47.4) | 0.082 | −0.008 |
| Abnormalities at auscultatione | 348/1029 (33.8) | 340/1018 (33.4) | 688/2047 (33.6) | 172/230 (74.8) | 177/542 (32.7) | 349/772 (45.2) | 0.952 | −0.087 |
| Disturbed sleep | 638/1035 (61.6) | 642/1022 (62.8) | 1280/2057 (62.2) | 172/232 (74.1) | 324/546 (59.3) | 496/778 (63.7) | 0.347 | −0.007 |
| Crackles | 63/1033 (6.1) | 63/1018 (6.2) | 126/2051 (6.1) | 67/232 (28.9) | 38/542 (7.0) | 105/774 (13.6) | 0.572 | −0.049 |
| Rhonchi | 143/1032 (13.9) | 138/1018 (13.6) | 281/2050 (13.7) | 76/230 (33.0) | 80/542 (14.8) | 156/772 (20.2) | 0.471 | −0.059 |
| Runny nose | 770/1035 (74.4) | 734/1022 (71.8) | 1504/2057 (73.1) | 165/233 (70.8) | 359/546 (65.8) | 524/779 (67.3) | 0.129 | −0.006 |
| Chest pain | 474/1034 (45.8) | 468/1021 (45.8) | 942/2055 (45.8) | 118/233 (50.6) | 244/546 (44.7) | 362/779 (46.5) | 0.136 | −0.009 |
| Muscle ache | 519/1035 (50.1) | 524/1022 (51.3) | 1043/2057 (50.7) | 132/233 (56.7) | 237/546 (43.4) | 369/779 (47.4) | 0.295 | −0.010 |
| Headache | 572/1035 (55.3) | 593/1023 (58.0) | 1165/2058 (56.6) | 126/233 (54.1) | 281/546 (51.5) | 407/779 (52.2) | 0.079 | 0.002 |
| Confusion | 31/1035 (3.0) | 52/1022 (5.1) | 83/2057 (4.0) | 12/233 (5.2) | 15/546 (2.8) | 27/779 (3.5) | 0.144 | 0.002 |
| Heart disease | 56/1036 (5.4) | 50/1023 (4.9) | 106/2059 (5.1) | 27/233 (11.6) | 39/545 (7.2) | 66/778 (8.4) | 0.136 | −0.006 |
↵a Data are n/N (%) unless otherwise stated.
↵b Chronic obstructive pulmonary disease, asthma, or other lung disease.
↵c Severity of symptoms: 1 = no problem, 2 = mild problem, 3 = moderate problem, 4 = severe problem.
↵d Yellow, green, or bloodstained.
↵e Represents the clinician’s report of hearing anything they judged to be abnormal on auscultation. SD = standard deviation.