Summary of GRADE evidence profile of antibiotics vs placebo or standard care
| Outcome/timeframe | Study results and measurements | Absolute effect estimates | Certainty in effect estimates (quality of evidence) | Plain text summary | |
| No antibiotics | Antibiotics | ||||
| Treatment failure/1 month | OR 0.58 (95% CI 0.37 to 0.90) Based on data from 2517 patients in eight studies Follow-up 7–21 days | 93 per 1000 | 56 per 1000 | Low Due to serious risk of bias and serious inconsistency* | Antibiotics probably reduce the risk of treatment failure. |
| Difference: 37 fewer per 1000 (95% CI 56 fewer—9 fewer) | |||||
| Treatment failure (antibiotics with activity against MRSA)/1 month | OR 0.45 (95% CI 0.33 to 0.62) Based on data from 2305 patients in six studies Follow-up 7–21 days | 128 per 1000 | 62 per 1000 | High | Antibiotics with activity against MRSA reduce the risk of treatment failure. |
| Difference: 66 fewer per 1000 (95% CI 82 fewer—45 fewer) | |||||
| Treatment failure (antibiotics without activity against MRSA)/1 month | OR 1.82 (95% CI 0.68 to 4.85) Based on data from 212 patients in two studies Follow-up 7–21 days | 58 per 1000 | 101 per 1000 | Moderate Due to serious imprecision† | Antibiotics without activity against MRSA may not reduce the risk of treatment failure. |
| Difference: 43 more per 1000 (95% CI 18 fewer—172 more) | |||||
| Recurrence within/1 month | OR 0.48 (95% CI 0.30 to 0.77) Based on data from 2134 patients in six studies Follow-up 7–30 days | 129 per 1000 | 66 per 1000 | Moderate Due to serious risk of bias and borderline inconsistency‡ | Antibiotics probably reduce the risk of early abscess recurrence. |
| Difference: 63 fewer per 1000 (95% CI 86 fewer—27 fewer) | |||||
| Late recurrence/1−3 months | OR 0.64 (95% CI 0.48 to 0.85) Based on data from 1111 patients in two studies Follow-up 63–90 days | 267 per 1000 | 189 per 1000 | Moderate Due to serious risk of bias, borderline imprecision§ | Antibiotics probably reduce the risk of late abscess recurrence. |
| Difference: 78 fewer per 1000 (95% CI 118 fewer—31 fewer) | |||||
| Hospitalisation/3 months | OR 0.55 (95% CI 0.32 to 0.94) Based on data from 1206 patients in two studies Follow-up 40–90 days | 39 per 1000 | 22 per 1000 | Moderate Due to serious imprecision¶ | Antibiotics probably reduce the risk of hospitalisation. |
| Difference: 17 fewer per 1000 (95% CI 26 fewer—2 fewer) | |||||
| Pain (tenderness)/(3–4 days) | OR 0.76 (95% CI 0.60 to 0.97) Based on data from 1057 patients in one study Follow-up 3–4 days | 559 per 1000 | 491 per 1000 | Moderate Due to serious imprecision** | Antibiotics probably increase the risk of pain at 3–4 days. |
| Difference: 68 fewer per 1000 (95% CI 126 fewer—8 fewer) | |||||
| Pain (tenderness)/(8–10 days) | OR 0.56 (95% CI 0.35 to 0.88) Based on data from 1057 patients in one study Follow-up 8–10 days | 101 per 1000 | 59 per 1000 | Moderate Due to serious imprecision†† | Antibiotics may not increase the risk of pain at 8–10 days. |
| Difference: 42 fewer per 1000 (95% CI 63 fewer—11 fewer) | |||||
| Additional surgical procedures within/1–3 months | OR 0.58 (95% CI 0.39 to 0.87) Based on data from 1013 patients in one study Follow-up 43–63 days | 136 per 1000 | 84 per 1000 | Moderate Due to serious imprecision‡‡ | Antibiotics probably increase the risk of additional surgical procedures. |
| Difference: 52 fewer per 1000 (95% CI 78 fewer—16 fewer) | |||||
| Infections in family members within/1 month | OR 0.58 (95% CI 0.34 to 1.01) Based on data from 1013 patients in one study Follow-up 7–14 days | 67 per 1000 | 40 per 1000 | Moderate Due to serious imprecision§§ | Antibiotics probably do not increase the risk of infection in family members. |
| Difference: 27 fewer per 1000 (95% CI 43 fewer—1 more) | |||||
| Invasive infections/1 month | OR 1.02 (95% CI 0.14 to 7.24) Based on data from 1057 patients in one study Follow-up 7–14 days | 4 per 1000 | 4 per 1000 | Moderate Due to serious imprecision¶¶ | Antibiotics probably do not reduce the risk of serious complications at 7–14 days. |
| Difference: 0 more per 1000 (95% CI 3 fewer—24 more) | |||||
| Invasive infections/3 months | OR 7.46 (95% CI 0.15 to 376.12) Based on data from 1013 patients in one study Follow-up 42–56 days | 0 per 1000 | 1 per 1000 | Moderate Due to serious imprecision*** | Antibiotics probably do not reduce the risk of serious complications at 42–56 days. |
| Difference: 2 more per 1000 (95% CI 4 fewer—8more) | |||||
Evidence have summarised at Magic App (www.magicapp.org/public/guideline/jlRvQn).
*Risk of bias: serious. There was substantial missing data/lost to follow-up: the results are not robust to worth plausible sensitivity analysis (assuming that missing patients from the control arms have the same rate of treatment failure as those with complete follow-up, and five times the rate of treatment failure in the patients who were lost to follow-up in the antibiotic arm); inconsistency: serious. Effects might differ in different type of antibiotics.
†Imprecision: serious. CI approaches no effect.
‡Risk of bias: serious. There was substantial missing data/lost to follow-up: the results are not robust to worth plausible sensitivity analysis; inconsistency: no serious. The magnitude of statistical heterogeneity was high, with I2=45%, but the direction of effect was similar in almost all trials, favouring antibiotics over no antibiotics.
§Risk of bias: serious. Incomplete data and/or large loss to follow-up: results are not sensitive to worst plausible sensitivity analysis: OR 1.48, 95% CI 0.55 to 3.96; imprecision: no serious. A single large study, and one small study contributed data to this outcome.
¶Imprecision: serious. CI approaches no effect.
**Imprecision: serious. Only data from one study, CI approaches no effect.
††Imprecision: serious. Only data from one study.
‡‡Imprecision: serious. Data from one study only.
§§Imprecision: serious. Only data from one study; CI include no effect.
¶¶Imprecision: serious. Only data from one study.
***Imprecision: serious. Only data from one study; CI include no effect.
GRADE, Grading of Recommendations Assessment, Development and Evaluation; MRSA, methicillin-resistant Staphylococcus aureus.