Abstract: Two RCTs involving 2024 patients (1502 adults and 522 children) were included in this review. Both RCTs excluded patients with suspected severe disease. It was not possible to pool the results due to incomplete data. Both included trials concluded that the use of chest radiographs did not result in a better clinical outcome (duration of illness and of symptoms) for patients with acute LRTIs. In the study involving children in South Africa, the median time to recovery was seven days (95% confidence interval (CI) six to eight days (radiograph group) and six to nine days (control group)), P value = 0.50, log-rank test) and the hazard ratio for recovery was 1.08 (95% CI 0.85 to 1.34). In the study with adult participants in the USA, the average duration of illness was 16.9 days versus 17.0 days (P value > 0.05) in the radiograph and no radiograph groups respectively. This result was not statistically significant and there were no significant differences in patient outcomes between the groups with or without chest radiograph. The study in adults also reports that chest radiographs did not affect the frequencies with which clinicians ordered return visits or antibiotics. However, there was a benefit of chest radiographs in a subgroup of the adult participants with an infiltrate on their radiograph, with a reduction in length of illness (16.2 days in the group allocated to chest radiographs and 22.6 in the non-chest radiograph group, P < 0.05), duration of cough (14.2 versus 21.3 days, P < 0.05) and duration of sputum production (8.5 versus 17.8 days, P < 0.05). The authors mention that this difference in outcome between the intervention and control group in this particular subgroup only was probably a result of "the higher proportion of patients treated with antibiotics when the radiograph was used in patient care". Hospitalisation rates were only reported in the study involving children and it was found that a higher proportion of patients in the radiograph group (4.7%) required hospitalisation compared to the control group (2.3%) with the result not being statistically significant (P = 0.14). None of the trials report the effect on mortality, complications of infection or adverse events from chest radiographs. Overall, the included studies had a low or unclear risk for blinding, attrition bias and reporting bias, but a high risk of selection bias. Both trials had strict exclusion criteria which is important but may limit the clinical practicability of the results as participants may not reflect those presenting in clinical practice. Data from two trials suggest that routine chest radiography does not affect the clinical outcomes in adults and children presenting to a hospital with signs and symptoms suggestive of a LRTI. This conclusion may be weakened by the risk of bias of the studies and the lack of complete data available.

Plain-language summary: Two trials with a total of 2024 participants were included in this review. The trial published in 1983 in the USA included only adults, while the trial in 1998 in South Africa included only children. Both trials were set in large metropolitan cities. We were unable to combine the results of the two studies due to incomplete data. However, both trials came to the same conclusion regarding the use of chest X-rays in chest infections, except in the subgroup of patients with evidence of infection (infiltrates) on their X-rays. In both adults and children, chest X-rays did not result in significant differences in recovery time. In summary, there were no differences in patient outcomes between the groups with or without chest X-ray. Although both studies suggest that chest X-rays do not improve patient outcomes, it is not clear if this finding can be applied to all populations and settings. Results may be different in resource poor countries. Our conclusions are limited due to the lack of complete data available and by the risk of bias of the studies. Adverse effects of chest X-rays were not assessed by either study. We assessed the quality of the evidence from both trials as being moderate. For the remainder of this review, X-rays will be referred to as radiographs. The evidence is current as of February 2013.