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Chest radiographs for acute lower respiratory tract infections

  1. Amy Millicent Y Cao1,
  2. Joleen P Choy1,
  3. Lakshmi Narayana Mohanakrishnan1,*,
  4. Roger F Bain1,
  5. Mieke L van Driel2,3,4

Editorial Group: Cochrane Acute Respiratory Infections Group

Published Online: 26 DEC 2013

Assessed as up-to-date: 5 FEB 2013

DOI: 10.1002/14651858.CD009119.pub2

How to Cite

Cao AMY, Choy JP, Mohanakrishnan LN, Bain RF, van Driel ML. Chest radiographs for acute lower respiratory tract infections. Cochrane Database of Systematic Reviews 2013, Issue 12. Art. No.: CD009119. DOI: 10.1002/14651858.CD009119.pub2.

Author Information

  1. 1

    Bond University, Faculty of Health Sciences and Medicine, Gold Coast, Queensland, Australia

  2. 2

    The University of Queensland, Discipline of General Practice, School of Medicine, Brisbane, Queensland, Australia

  3. 3

    Bond University, Centre for Research in Evidence-Based Practice, Gold Coast, QLD, Australia

  4. 4

    Ghent University, Department of General Practice and Primary Health Care, Ghent, Belgium

*Lakshmi Narayana Mohanakrishnan, Faculty of Health Sciences and Medicine, Bond University, University Drive, Gold Coast, Queensland, 4229, Australia.

Publication History

  1. Publication Status: New
  2. Published Online: 26 DEC 2013


Characteristics of included studies [ordered by study ID]
Bushyhead 1983

MethodsRandomised controlled trial (Phase III: February 1977 to February 1979)

3-phase study

ParticipantsThe study was conducted with 2018 consecutive patients (1502 in Phase III) at emergency room and walk-in clinic of "Brooke Army Medical Center at Fort Sam Houston, Texas"

"The 2018 patients in the three phases of this study were predominantly retired military personnel and military dependents; a minority were active-duty Army troops. Most Participants were Caucasian (79 per cent). There were more women than men; the patients' ages were distributed bimodally with peaks at 13 to 20 and 51 to 60 years, with a mean age of 38."

Inclusion criteria: "Consenting, nonpregnant, adult patients seeking medical care for the first time for coughs of less than one month's duration"

Exclusion criteria: pulse rate of 160 or more, temperature 104 °F (40 °C) or more, systolic blood pressure 90 mmHg or lower, patients arriving by stretcher

Interventions"The independent variable in this randomised, controlled trial is the availability to the physician of the chest film results. Dependent variables are the physicians' management plans and the patient outcomes."

Phase I

- Chest radiographs were only taken on physicians' request and all requested radiographs were seen

- Resembles normal physician practice

- "The physicians did not try to predict chest radiograph findings and did not make assessments and plans before seeing the films"

- N = 199

Phase II

- Chest radiographs taken of all patients

- Physicians saw chest radiographs only if they ordered them

- Second physician reviewed chest radiographs and clinical records of patients whose films were not seen and intervened when plans were dangerously inappropriate

- N = 288

Phase III

- PA (Posterior to Anterior) and lateral chest radiographs taken of all patients

- Determined by lot with 1:1 odds randomisation for whether physicians would receive the radiology report and chest radiograph

- The physicians recorded their estimate of the most likely finding on the chest radiograph, the probability of this finding, the probability of an infiltrate on the chest radiograph and the probable microbiological cause of the illness

- Physicians wrote down whether they wished to order a chest radiograph and why they wanted to. This had no bearing on whether physicians saw the radiographs

- Physicians randomised to the intervention group were allowed to change diagnosis and management plans on the basis of radiology results

- N = 1502 (chest radiographs provided in 739 patients, radiographs not provided in 763)

OutcomesThe effect of chest radiographs on the management and clinical course of patients with acute cough

- "Effectiveness of pneumonia diagnosis and treatment"

- "Effect of the chest film on physicians' plans"

- "Effect of chest radiograph on illness outcome"

- "Effect of study design on physicians' decisions"

Notes"Evaluation of the usefulness of chest radiographs in the care of patients presenting for the first time with acute cough"

"We assume that a test is valuable if its use results in effective changes in patient management plans or better patient outcomes."

Only Phase III results were relevant to our review - hence only Phase III results were discussed

Risk of bias

BiasAuthors' judgementSupport for judgement

Random sequence generation (selection bias)Unclear riskPhase I - "To ensure a study population comparable with that of Phase III, in Phase I we selected for participation only patients who verbally agreed to the Phase III protocol"

Phase III - "We determined by lot, with 1:1 odds, whether or not the physician caring for the patient would receive the chest films and the radiologist's readings"

It is not described how the random numbers or "lot" were generated

Allocation concealment (selection bias)Low risk"The physicians had to make their diagnostic, treatment, and follow-up decisions before patient randomisation but after the clinical evaluation of the patient. These plans could be revised only if the patient were randomised to the group whose chest films and radiologists' readings were made available, and then only after the physician reviewed this information."

Phase I

- "Chest films were taken only on physicians' requests, and the physicians saw all requested chest radiographs"

- "This phase resembled ordinary physician practice"

- Allocation concealment not applicable as this phase aims to model the day-to-day practice for a 'gold standard'

Phase II

- "We took chest radiographs of all patients. However, physicians saw the chest films only if they had ordered them."

Phase III

- "Without knowledge of chest film results... physicians reviewed and checked the history and performed a standard physical examination"

- "We required clinicians to record diagnoses and management plans for all patients before they knew whether or not they would see the chest films...They noted whether they wished to order a chest radiograph for the patient and if so, why. These decisions had no bearing on whether the physicians saw the radiographs."

Blinding of outcome assessment (detection bias)
All outcomes
High risk"Primary outcome (time to recovery) assessed blind to treatment group. Assessment of secondary outcomes was not blinded."

"Radiology residents, with staff radiologists available for consultation, read each chest radiograph. The only clinical information available to them was that the patient had an acute cough. When available, previous chest films were used in reading the films... "

"Without knowledge of chest film results, research assistants collected a standard history from all patients."

Incomplete outcome data (attrition bias)
All outcomes
Low riskAnalysis was by intention-to-treat

"However, when physicians felt that viewing the films was essential to the patients' health, the patients were excluded from randomisation, and physicians saw their chest films. This occurred with only 2 per cent of patients."

Selective reporting (reporting bias)Low riskNo trial protocol was available. However, all outcomes were reported

Other biasUnclear risk"For ethical reasons, a physician not otherwise active in the study reviewed the medical records and chest films of all patients whose films were not given to their physicians. The reviewing physician did not intervene in the patient's care unless management plans seemed dangerously inappropriate."

"As in Phase III, a second physician reviewed the radiographs and clinical records of all patients whose films were not seen by their clinicians, and intervened when plans were believed dangerously inappropriate."

No conflicts of interest and financial disclosures reported

Swingler 1998

MethodsRandomised controlled trial (September 1995 to September 1996 "on weekday mornings")

Participants581 patients enrolled. 522 allocated to radiograph or to the control group (59 excluded)

Inclusion criteria:

"Children aged 2 to 59 months who presented to the Red Cross Children's Hospital [Cape Town] as their first contact were eligible for this study if they met the WHO case definition for pneumonia (i.e. cough and tachypnoea but drinking well and without chest indrawing, cyanosis, abnormal level of consciousness or stridor)."

"Tachypnoea was defined as a respiratory rate of 50 breaths or more/min in children aged 2 to 11 months, and 40 breaths or more/min in children aged 12 months or more."

Exclusion criteria: "cough of more than 14 days duration, history of current household contact with active tuberculosis, a localised wheeze, clinical signs of cardiac failure or the clinician's assessment that a chest radiograph was mandatory"

"The study was done in the primary general outpatients section. Patients were enrolled from September, 1995, to September, 1996, on weekday mornings. An experienced registered nurse screened all waiting patients, and identified eligible individuals. Baseline information collected at this stage included age, weight, duration of symptoms before presentation, and respiratory rate."

N = 522

Interventions"Eligible patients identified by the nurse were seen by a clinician. After the medical history of each patient was taken and an examination done, eligible patients were allocated to the radiograph or to the control group."

"The intervention was the use of a chest radiograph (anteroposterior and lateral views). The chest radiograph was viewed by the clinician and a routine report supplied by the duty paediatric radiologist or radiology registrar was available with the films. The control was standard of care without a chest radiograph. All other management was entirely at the discretion of the clinician."

- N = 286 allocated to have chest radiograph

- 13 did not have it done - 273 children X-rayed

Outcomes"The primary outcome measure was time to recovery, measured by twice weekly structured telephone interviews of the subset of 295 participants contactable by telephone."

"Respondents were asked 'Is (child's name) completely well yet?' If the answer was 'Yes', the next questions was 'On what day was he/she last sick?'. Answers to three of the questions in the questionnaire (subsequent visits and admissions to the Children's Hospital and subsequent chest radiographs done there) were verified by examination of the clinical records"

"Subsidiary outcomes were management options used (additional tests ordered, number of drugs per prescription, antibiotic use, follow-up appointment, and immediate admission to hospital) and other clinical outcomes (return visits and later hospital admission). All subsidiary outcomes were ascertained by examination of clinical records of all patients by the principal investigator (whether contactable by telephone or not), except for visits to facilities other than the Children's Hospital, which were measured by the above telephone interview."

Notes"The aim of this study was to quantify the effect of the use of chest radiographs on the management and clinical outcome in children with ambulatory acute lower respiratory tract infection, and to determine whether any such effect was dependent on the experience of the clinician"

Risk of bias

BiasAuthors' judgementSupport for judgement

Random sequence generation (selection bias)High risk"..the random allocation [was] generated in advance by the principal investigator (by tossing a coin)."

Allocation concealment (selection bias)High risk"Allocation was done by the clinician opening a sealed sequentially numbered manila envelope attached to the consultation sheet and containing the random allocation..."

"If a patient was excluded by the clinician before randomisation the sealed envelope was returned to the principal investigator. The return of envelopes was audited."

"There were no differences in baseline characteristics between groups or between randomised and excluded patients."

Blinding of outcome assessment (detection bias)
All outcomes
Low risk"The telephone interviewer was not informed of the study hypothesis, was blind to the randomisation status of the patients, and had no contact with the hospital other than through the principal investigator. On casual enquiry at the end of the study, the interviewer had guessed only that the study dealt with chest infections."

"Coding and cleaning of telephone questionnaire data was done without knowledge of treatment group by the principal investigator on a separate data capture sheet and in a separate database."

Incomplete outcome data (attrition bias)
All outcomes
High risk"Patients were analyzed by intention-to-treat"

"Of the 581 eligible patients identified by the registered nurse, 59 (26 contactable by telephone) were excluded by the clinicians before randomisation. The remaining 522 patients were randomly allocated, 259 to the radiograph group and 263 to the control group. Four (1.5%) patients in the radiograph group did not receive the intervention whereas 7 (2.7%) of the control group had a radiograph on the day of randomisation"

"295 (77.5%) of the patients providing a telephone number were followed till recovery or censored at 28 days. Of the 522 participants 518 (99.2%) record sheets of the first consultation were retrieved, and all 522 folders for assessment of subsequent visits."

"Although 22% of participants who had a telephone number were lost to follow-up: loss was similar between treatment groups. In addition, the lack of effect of a chest radiograph measured by telephone interview is consistent with the lack of effect on outcomes measured by examination of clinical records, where follow-up was virtually complete."

Selective reporting (reporting bias)Low riskNo trial protocol was available. However, all outcomes were reported

Other biasUnclear risk"Reliability of record review was assessed by repeat examination of a 10% random sample of clinical records by a second observer not involved in the study. 12 items were assessed: exclusion before randomisation, treatment allocation, clinician's perceived need for chest radiograph, diagnosis, and the outcome variable listed..."

No conflicts of interest and financial disclosures reported. However, "this study was supported by the Medical Research Council of South Africa and the University of Cape Town."

Note: potential recruitment bias as "Patients were enrolled from September 1995 to September 1996 on weekday mornings."

Characteristics of excluded studies [ordered by study ID]

StudyReason for exclusion

Bourayou 2011Not a randomised controlled trial. "We have attempted to clarify [chest radiographs'] diagnostic value in community acquired pneumonia in children through a literature review..."

Briel 2006Study outcomes not relevant to our review outcomes:

"Prevalence of diagnostic tests"

"Association between patient characteristics and use of tests"

"Association between test results and diagnosis and treatment"

"Association between test use and patient satisfaction and enablement"

"GPs relied on test results when making decisions about diagnosis & antibiotic treatment". However, study does not distinguish between chest radiographs and other blood tests

Colucci 2012"One year retrospective study of 2 community hospitals..."

"To determine if the disposition and therapeutic interventions for the children directly correlate to the radiography"

Lynch 2004Outcomes not relevant to our review outcomes. "The primary outcome variable was the difference in the sensitivity and specificity of the emergency physicians' interpretations of chest radiographs with access to two views (frontal and lateral) versus one view (frontal for children with suspected pneumonia."

"A secondary outcome included the change in management provided by the review of the two views by the radiologist."

Ralston 2012Not a randomised controlled trial. "Our objective was to reduce utilization of unnecessary therapies in the inpatient care of bronchiolitis across a diverse network of clinical sites"

"We formed a voluntary quality improvement collaborative of paediatric hospitals for the purpose of benchmarking the use of bronchodilators, steroids, chest radiography, chest physiotherapy, and viral testing in bronchiolitis using hospital administrative data. We shared resources within the network, including protocols, scores, order sets, and key bibliographies, and established group norms for decreasing utilization."

Swingler 2000Not a randomised controlled trial. Appears to be a selected case review of tuberculosis of a previously published study (Swingler 1998). Swingler 1998 is already included in our review

Comparison 1. Chest radiograph versus management without chest radiograph (children only)

Outcome or subgroup titleNo. of studiesNo. of participantsStatistical methodEffect size

 1 Time to resolution of clinical signs and symptoms1518Mean Difference (IV, Fixed, 95% CI)0.0 [-1.81, 1.81]

 2 Hospitalisation rates1518Risk Ratio (M-H, Fixed, 95% CI)2.03 [0.77, 5.33]

Summary of findings for the main comparison.

The effectiveness of chest radiographs in addition to clinical judgement compared with clinical judgement alone for acute lower respiratory tract infections

Patient or population: adults and children with clinical signs and symptoms of acute lower respiratory tract infection

Settings: South Africa and USA

Intervention: chest radiographs and clinical judgement

Comparison: clinical judgement alone, without the use of chest radiographs

OutcomesIllustrative comparative risks* (95% CI)No. of participants
Quality of the evidence

Without chest radiograph (control)With chest radiograph

MortalityAdults----Not assessed

Children00518 (1)⊕⊕⊕⊝
Not included as an outcome, however it was reported that "no deaths were recorded" during the trial

Time to resolution of clinical signs and symptoms

Adults17.016.91502 (1)⊕⊕⊝⊝
Average duration of illness in the radiograph group was 16.9 days and 17.0 days in the no radiograph group (P > 0.05)

Relative risks not provided in original RCT

Inadequate data provided in original RCT - further analysis of these data could not be conducted as a specific P value was not stated (only whether the P value was greater or less than 0.05)

Follow-up continued to either end of illness or for at least 1 month after presentation

Downgraded to low quality due to risk of bias and the lack of evidence that the estimate excludes clinically meaningful differences in either direction

Children7 (95% CI 6 to 9)7 (95% CI 6 to 8)518 (1)⊕⊕⊝⊝
Median time to recovery in control group was 7 days (95% CI 6 to 9 days) and in the chest radiograph group was 7 days (95% CI 6 to 8 days)

P = 0.50, log-rank test

Hazard ratio for recovery was 1.08 (95% CI 0.85 to 1.34)

Follow-up until recovery or censored at 28 days

Downgraded to low quality due to risk of bias and the lack of evidence that the estimate excludes meaningful differences in either direction

Hospitalisation ratesAdults----Not reported. Data only provided in subgroup of patients that was not randomised

Children2.3% (6 of 261 children)4.7% (12 of 257 children)518 (1)⊕⊕⊝⊝
The estimated risk ratio for this study was 2.03 (0.77 to 5.03). Not statistically significant (P = 0.154)

Downgraded to low quality due to risk of bias and imprecision of data

Complications of infectionAdults----Not assessed

Children----Not assessed

Adverse effects from chest radiographsAdults----Not assessed

Children----Not assessed

*The basis for the assumed risk (e.g. the median control group risk across studies) is provided in footnotes. The corresponding risk (and its 95% confidence interval) is based on the assumed risk in the comparison group and the relative effect of the intervention (and its 95% CI).
CI: confidence interval; P: P value; NNT: number needed to treat; RCT: randomised controlled trial; RR: risk ratio

GRADE Working Group grades of evidence
High quality: Further research is very unlikely to change our confidence in the estimate of effect.
Moderate quality: Further research is likely to have an important impact on our confidence in the estimate of effect and may change the estimate.
Low quality: Further research is very likely to have an important impact on our confidence in the estimate of effect and is likely to change the estimate.
Very low quality: We are very uncertain about the estimate.

 Bushyhead 1983: limitations in the design and implementation of available studies suggesting high risk for detection bias and low or unclear risk for selection, attrition and reporting bias (Risk of bias in included studies).
Swingler 1998: limitations in the design and implementation of the study suggesting high risk for selection and attrition bias and low risk for detection and reporting bias (Risk of bias in included studies).
No serious risk of unexplained heterogeneity or publication bias in either of the trials. Both outcomes for time to resolution of symptoms and hospitalisation rates in both trials were downgraded to 'low quality' due to imprecision of results.
A column for relative effects was not included as part of the 'Summary of findings' table as data needed to calculate relative risks were not presented in either of the included trials.
Although mortality in children did not occur, we have included this in our  Summary of findings for the main comparison as it may reflect the severity of illness and the use of appropriate management.
Table 1. Time to resolution of clinical signs and symptoms (children only)

StudyChest radiographWithout chest radiograph

Median (days)SDTotalMedian (days)SDTotal

Swingler 199878.2257712.4261

 Chest radiograph versus management without chest radiograph (children only), outcome: 1.1 Time to resolution of clinical signs and symptoms.