Emergency (****); * (*): *-* This open-access article distributed under the terms of the Creative Commons Attribution NonCommercial 3.0 License (CC BY-NC 3.0). Copyright © 2016 Shahid Beheshti University of Medical Sciences. All rights reserved. Downloaded from: www.jemerg.com 55 Emergency (2016); 4 (2): 55-64 REVIEW ARTICLE Comparison of Ultrasonography and Radiography in Detection of Thoracic Bone Fractures; a Systematic Review and Meta-Analysis Mahmoud Yousefifard1, Masoud Baikpour2, Parisa Ghelichkhani3, Hadi Asady4, Abolfazl Darafarin5, Mohammad Reza Amini Esfahani5, Mostafa Hosseini6, 7*, Mehdi Yaseri6, Saeed Safari5 1. Department of Physiology, School of Medicine, Tehran University of Medical Sciences, Tehran, Iran. 2. Department of Medicine, School of Medicine, Tehran University of Medical Sciences, Tehran, Iran. 3. Department of Intensive Care Nursing, School of Nursing and Midwifery, Tehran University of Medical Sciences, Tehran, Iran. 4. Department of Occupational Health Engineering, Faculty of Public Health, Tehran University of Medical Sciences, Tehran, Iran. 5. Department of Emergency Medicine, Shohadaye Tajrish Hospital, Shahid Beheshti University of Medical Sciences, Tehran, Iran. 6. Sina Trauma and Surgery Research Center, Tehran University Medical Sciences, Tehran, Iran. 7. Department of Epidemiology and Biostatistics, school of Public Health, Tehran University of Medical Sciences, Tehran, Iran. *Corresponding Author: Mostafa Hosseini, Department of Epidemiology and Biostatistics School of Public Health, Tehran University of Medical Scienc es, Poursina Ave, Tehran, Iran; Email: mhossein110@yahoo.com; Tel: +982188989125; Fax: +982188989127. Received: June 2015; Accepted: August 2015 Abstract Introduction: The potential benefit of ultrasonography for detection of thoracic bone fractures has been proven in various surveys but no comprehensive conclusion has been drawn yet; therefore, the present study aimed to conduct a thorough meta-analytic systematic review on this subject. Methods: Two reviewers independently car- ried out a comprehensive systematic search in Medline, EMBASE, ISI Web of Knowledge, Scopus, Cochrane Library, and ProQuest databases. Data were summarized as true positive, false positive, true negative and false negative and were analyzed via STATA 11.0 software using a mixed-effects binary regression model. Sources of heterogene- ity were further assessed through subgroup analysis. Results: Data on 1667 patients (807 subjects with and 860 cases without thoracic fractures), whose age ranged from 0 to 92 years, were extracted from 17 surveys. Pooled sensitivity and specificity of ultrasonography in detection of thoracic bone fractures were 0.97 (95% CI: 0.90-0.99; I2= 88.88, p<0.001) and 0.94 (95% CI: 0.86-0.97; I2= 71.97, p<0.001), respectively. The same measures for chest radiography were found to be 0.77 (95% CI: 0.56-0.90; I2= 97.76, p<0.001) and 1.0 (95% CI: 0.91-1.00; I2= 97.24, p<0.001), respectively. The sensitivity of ultrasonography was higher in detection of rib fractures, compared to fractures of sternum or clavicle (97% vs. 91%). Moreover, the sensitivity was found to be higher when the proce- dure was carried out by a radiologist in comparison to an emergency medicine specialist (96% vs. 90%). Conclu- sion: Base on the findings of the present meta-analysis, screening performance characteristic of ultrasonography in detection of thoracic bone fractures was found to be higher than radiography. However, these characteristics were more prominent in detection of rib fractures and in cases where was performed by a radiologist. Key words: Thoracic fractures; ultrasonography; radiography; diagnostic tests, routine Cite this article as: Yousefifard M, Baikpour M, Ghelichkhani P, et al. Comparison of ultrasonography and radiography in detec- tion of thoracic bone fractures; a systematic review and meta-analysis. Emergency. 2016; 4(2):55-64. Introduction: arly diagnosis of rib fractures can rapidly indicate the source of thoracic pain and be helpful in pain management of trauma patients. Other than pain, rib fractures have been reported to be associated with morbidity and mortality in elderly patients (3-5). In most emergency departments, ultrasonography is con- sidered as one of the most useful screening tools for rapid evaluation of trauma patients (6). Application of ultrasonography for assessment of chest wall injuries has been reported from 1980s (7). Since then the tech- nology of ultrasound devices has significantly improved so that images with higher resolutions are obtained. In light of these improvements, the diagnostic value of this modality has been considerably enhanced (9). In this re- gard, studies have illustrated a considerably high diag- nostic value of ultrasonography in detection of thoracic fractures, even higher than that of chest radiography (8, 10-12). For instance in his narrative review, Chan re- ferred to ultrasonography as a reliable diagnostic tool E This open-access article distributed under the terms of the Creative Commons Attribution NonCommercial 3.0 License (CC BY-NC 3.0). Copyright © 2016 Shahid Beheshti University of Medical Sciences. All rights reserved. Downloaded from: www.jemerg.com Yousefifard et al 56 for detection of thoracic bone fractures (13). Neverthe- less, still no comprehensive review has been carried out comparing the diagnostic values of chest ultrasonogra- phy and radiography in detection of thoracic fractures. One solution is to perform a meta-analysis on the availa- ble evidence (15, 16). Accordingly, the present system- atic review and meta-analysis aimed to determine the di- agnostic values of chest ultrasonography and radiog- raphy in detection of thoracic bone fractures. Methods: Search strategy and selection criteria The study protocol was established based on the guide- lines of Meta-analysis of Observational Studies in Epide- miology statement (MOOSE) (19). After selection of key- words from Medical Subject Heading (MeSH) terms and EMTREE, two reviewers (M.Y, P.G) independently car- ried out an extended systematic search in databases of Medline (via PubMed), EMBASE (via OvidSP), ISI Web of Knowledge, Scopus, Cochrane Library, and ProQuest without any time or language limitations. The keywords included “Ultrasonography” OR “Sonography” OR “Ultra- sound” OR “Radiography” OR “Chest Film” OR “Chest Ra- diograph” combined with “Rib Fractures” OR “Chest Wall Fracture” OR “Sternum Fracture” OR “Sternal Fracture” OR “Clavicle Fracture” OR “Scapula Fracture”. Addition- ally, the bibliographies of original and review articles as well as Google Scholar were also searched. All the studies evaluating the diagnostic accuracy of ultrasonography or chest radiography in detection of chest wall fractures were assessed. Review and editorial articles, case re- ports and studies with sample populations of less than 10 patients were excluded. Data extraction Two reviewers (M.Y, P.G) independently worked on summarizing the data regarding assessing quality of studies, baseline characteristics of patients (age, gender, the number of patients with and without hemothorax, the etiology of hemothorax), the characteristics of ultra- sonography device (transducer, frequency), physicians in charge of imaging interpretation, blinding status, sam- pling method (consecutive, convenience), study design Figure 1: Flowchart of the study. This open-access article distributed under the terms of the Creative Commons Attribution NonCommercial 3.0 License (CC BY-NC 3.0). Copyright © 2016 Shahid Beheshti University of Medical Sciences. All rights reserved. Downloaded from: www.jemerg.com 57 Emergency (2016); 4 (2): 55-64 T a b le 1 : C h a re ct e ri st ic s o f in cl u d e d s tu d ie s S tu d y N o . o f p a ti e n t (+ / - ) A g e 1 ( y e a r s ) M a le ( % ) R e fe r e n c e / In d e x T r a n s d u c e r / O p e r a to r S a m p li n g / F r a c tu r e W e a k n e s s e s H e n d r ic h 1 9 9 5 ( 1 ) 1 5 / 3 0 4 5 ( 2 9 -6 1 ) 5 7 .8 C X R / U S 7 .5 M H z / R a d io lo g is t C o n v e n ie n ce / st e rn u m L o w s a m p le s iz e P o ss ib il it y o f se le ct io n b ia s E n g in 2 0 0 0 (2 ) 1 8 / 5 3 5 .4 ( 1 8 -7 5 ) 8 2 .6 C X R / U S 7 .5 M H z / R a d io lo g is t C o n v e n ie n ce / S te rn u m R e tr o sp e ct iv e d e si g n L o w s a m p le s iz e P o ss ib il it y o f se le ct io n b ia s H u r le y 2 0 0 4 (8 ) 1 5 / 5 3 1 ( 1 6 -5 5 ) 7 8 .6 C T / U S , C X R 1 2 .5 M H z / R a d io lo g is t C o n se cu ti v e / R ib L o w s a m p le s iz e R a in e r 2 0 0 4 (1 1 ) 7 6 / 1 2 5 1 ± 1 9 5 9 C T / U S , C X R 5 -t o 1 0 -M H z / R a d io lo g is t C o n v e n ie n ce / S te rn u m Ji n 2 0 0 6 (1 0 ) 2 3 / 1 6 4 5 .2 ( 1 5 -8 2 ) 5 2 C T / U S , C X R 5 -t o 9 -M H z / R a - d io lo g is t C o n v e n ie n ce / M u lt ip le L o w s a m p le s iz e P o ss ib il it y o f se le ct io n b ia s T r a u b 2 0 0 7 (1 4 ) 6 8 / 7 3 4 7 .2 ( 1 8 -8 9 ) 7 5 C T / C X R N A / R a d io lo g is t C o n v e n ie n ce / R ib R e tr o sp e ct iv e d e si g n P o ss ib il it y o f se le ct io n b ia s W o o tt o n - G o r g e s 2 0 0 8 ( 1 7 ) 1 3 1 / 9 4 0 .2 ( 0 .1 -0 .5 ) 4 1 .7 C T / C X R N A / R a d io lo g is t C o n se cu ti v e / R ib R e tr o sp e ct iv e d e si g n P o ss ib il it y o f se le ct io n b ia s L o w s a m p le s iz e C r o s s 2 0 1 0 (1 8 ) 4 3 / 5 7 1 0 .7 ( 1 -1 7 ) 8 7 .3 C X R / U S 1 0 - to 1 5 -M H z / E P C o n v e n ie n ce / C la v ic le P o ss ib il it y o f se le ct io n b ia s W e in b e r g 2 0 1 0 ( 2 0 ) 2 5 / 1 8 7 1 3 ( 3 -2 3 ) N R C T / U S 7 .5 - to 1 0 -M H z / E P C o n v e n ie n ce / C la v ic le a n d r ib P o ss ib il it y o f se le ct io n b ia s Y o u 2 0 1 0 (2 1 ) 2 4 / 1 2 4 3 ( 8 -7 3 ) 5 2 .8 C T / U S 7 -t o 1 2 -M H z / R a d io lo g is t C o n se cu ti v e / R ib L o w s a m p le s iz e S z u c s -F a r - k a s 2 0 1 1 (2 2 ) 3 9 / 2 4 6 4 .4 ± 1 4 .7 7 3 C T / C X R N A / R a d io lo g is t C o n v e n ie n ce / R ib R e tr o sp e ct iv e d e si g n L o w s a m p le s iz e P o ss ib il it y o f se le ct io n b ia s Y a z k a n 2 0 1 2 ( 2 3 ) 8 3 / 8 3 4 0 .8 ( 1 6 -9 2 ) 7 3 .5 C T / C X R N A / S u rg e o n C o n se cu ti v e / R ib R e tr o sp e ct iv e d e si g n B ła s iń s k a 2 0 1 3 ( 2 4 ) 3 4 / 2 6 N R N R C T / C X R N A / R a d io lo g is t C o n se cu ti v e / M u lt ip le L o w s a m p le s iz e C h a r d o li 2 0 1 3 ( 2 5 ) 5 1 / 1 4 9 3 7 .9 ( 1 6 - 9 0 ) 8 4 C T / C X R N A / E P C o n v e n ie n ce / R ib T h e i n te rp re ta ti o n o f th e C X R a n d C T w e re n o t in b li n d f a sh io n P o ss ib le s e le ct io n b ia s U z u n 2 0 1 3 (1 2 ) 9 2 / 8 2 8 ( 1 5 - 4 0 ) 7 3 C T / U S , C X R N R / R a d io lo g is t C o n se cu ti v e / R ib P o ss ib il it y o f re p o rt in g b ia s H o ff s te tt e r 2 0 1 4 ( 2 6 ) 1 5 / 2 4 6 1 ( 2 4 -8 7 ) 6 0 .7 C T / C X R N A / R a d io lo g is t C o n se cu ti v e / M u lt ip le R e tr o sp e ct iv e d e si g n L o w s a m p le s iz e P a r k 2 0 1 5 (2 7 ) 5 5 / 5 5 5 6 .2 ( 1 6 .9 ) 5 7 .4 C T / C X R N A / R a d io lo g is t C o n se cu ti v e / R ib L o w s a m p le s iz e 1 , ( + / - ): n u m b e r o f p a ti e n t w it h f ra ct u re / n u m b e r o f p a ti e n t w it h o u t fr a ct u re ; 2 , N u m b e r a re p re se n te d a s m e a n ± s ta n d a rd d e v ia ti o n o r (r a n g e ). C T : C o m p u te d t o m o g ra p h y ; C X R : C h e st r a d io g ra p h y ; E P : E m e rg e n cy p h y si ci a n ; N A : N o t a p p li ca b le ; N R : N o t R e p o rt e d ; U S : U lt ra so n o g ra p h y . This open-access article distributed under the terms of the Creative Commons Attribution NonCommercial 3.0 License (CC BY-NC 3.0). Copyright © 2016 Shahid Beheshti University of Medical Sciences. All rights reserved. Downloaded from: www.jemerg.com Yousefifard et al 58 (retrospective, prospective). Finally the number of true positive (TP), true negative (TN), false positive (FP), and false negative (FN) cases were extracteded. Disagree- ments were discussed with the third reviewer (M.H) and a solution was proposed. In cases of data inaccessibility, the corresponding authors of the articles were con- tacted. Data presented as charts were extracted via the method proposed by Sistrom and Mergo (28). In cases where only the sensitivity and specificity were pre- sented, reliable web-based programs were used to calcu- late the number of TP, TN, FP, and FN cases. Quality assessment Quality of the studies were assessed based on the guide- lines of 14-Item Quality Assessment of Diagnostic Accu- racy Studies (QUADAS2) tool (29). The quality assess- ment were performed based on following items: ac- ceptable reference tests, accounting for indeterminate results, avoiding differential verification bias, disease progression bias, incorporation bias and verification bias, blind index test interpretation, blind interpretation of reference test, explained withdrawal, relevant clinical data available, and representative spectrum. A total grading of poor, fair, and good was attributed to each survey and only the fair and good studies were included in the meta-analysis. Statistical analysis Analysis was performed using STATA 11.0 statistical software via MIDAS module. To evaluate the screening performance characteristics of ultrasonography and ra- diography in detection of chest wall fractures, summary receiver operative curves (SROCs) were drawn and pooled sensitivity, specificity, positive likelihood ratio and negative likelihood ratio with 95% confidence inter- val (95% CI) were calculated. Due the high heterogeneity between the included studies, mixed-effects binary re- gression model was used. Heterogeneity was evaluated through calculations of I2 and χ2 tests and a P value of less than 0.1 together with an I2 greater than 50% were considered as positive heterogeneity (30). Subgroup analysis was performed to identify the source of hetero- geneity. Deek’s asymmetry funnel plot was used to search for publication bias. In all the analyses, p value of less than 0.05 was considered as statistically significant. Results: Study characteristics 17 out of 3894 studies found in the comprehensive search were included in the systematic review and meta- analysis (1, 2, 8, 10-12, 14, 17, 18, 20-27). 5 studies had assessed the diagnostic accuracy of ultrasonography in detection of thoracic bone fractures (1, 2, 18, 20, 21), 8 diagnostic value of chest radiography (14, 17, 22-27), and 4 diagnostic values of ultrasonography and radiog- raphy simultaneously (8, 10-12). 1667 cases (807 with and 860 without fractures) were extracted from the 17 mentioned articles, whose age ranged from 0 to 92 years old. Figure 1 shows the inclusion process of articles and table 1 summarizes the characteristics of included stud- ies. No publication bias was observed (Figure 2). Meta-analysis The results of the analyses are presented as SROCs and Funnel plots in Figures 3 to 5. The area under the curve of SROC for ultrasonography and radiography in detec- tion of chest wall fractures were found to be 0.99 (95% CI: 0.97-0.99) and 0.97 (95% CI: 0.96-0.99), respectively (Figure 3). Pooled sensitivity and specificity of ultraso- nography in detection of thoracic bone fractures were 0.97 (95% CI: 0.90-0.99; I2= 88.88, p<0.001) and 0.94 (95% CI: 0.86-0.97; I2= 71.97, p<0.001), respectively (Figure 4-A). These characteristics for radiography were found to be 0.77 (95% CI: 0.56-0.90; I2= 97.76, p<0.001) and 1.0 (95% CI: 0.91-1.00; I2= 97.24, p<0.001), respec- tively (Figure 5-A). In addition, pooled positive and neg- ative likelihood ratios of ultrasonography were 16.26 (95% CI: 6.26-38.87; I2= 59.14, p<0.001) and 0.03 (95% CI: 0.01-0.11; I2= 86.76, p<0.001), respectively (Figure 4-B), while these measures for radiography were re- ported to be 774.63 (95% CI: 7.0-8573.0; I2= 96.62, p<0.001) and 0.23 (95% CI: 0.11-0.48; I2= 96.94, p<0.001), respectively (Figure 5-B). Subgroup Analysis There were significant heterogeneity between the arti- cles (Figure 4 and 5). Subgroup analysis was performed to remove its effects and find its probable sources. Table 2 presents the results of this analysis. Specificity of ultra- sonography in detection of thoracic bone fractures was directly correlated with frequency of transducer (90% vs. 95%). The sensitivity of this modality was found to be higher in detection of rib fractures rather than fractures of clavicle or sternum (97% vs. 91%). Moreover it was found that the sensitivity would be higher if the proce- dure is performed by a radiologist (96%) compared to an emergency medicine specialist (90%). Sample size was another source of heterogeneity. Studies with sam- ple sizes of greater than 100 patients reported higher di- agnostic accuracies for ultrasonography in detection of thoracic bone fractures (97% vs. 91%). As can be seen in Table 2, the most important factor af- fecting sensitivity of chest radiography is the interpret- ing physician. The sensitivity was found to be 66% when the radiogram was interpreted by an emergency medi- cine specialist while it was 80% when interpreted by a radiologist. Furthermore, consecutive sampling method compared with convenience (80% vs. 73%) and sample size of more than 100 patients (82% vs. 73%) were also found to be sources of heterogeneity. Discussion: Base on the results of the present meta-analysis sensitiv- ity of chest ultrasonography in detection of thoracic This open-access article distributed under the terms of the Creative Commons Attribution NonCommercial 3.0 License (CC BY-NC 3.0). Copyright © 2016 Shahid Beheshti University of Medical Sciences. All rights reserved. Downloaded from: www.jemerg.com 59 Emergency (2016); 4 (2): 55-64 T a b le 2 : S u b g ro u p a n a ly si s o f d ia g n o st ic a cc u ra cy f o r ch e st r a d io g ra p h y a n d u lt ra so n o g ra p h y i n d e te ct io n o f th o ra ci c b o n e f ra ct u re s N o . o f s tu d ie s B iv a r ia te r a n d o m -e ff e c t m o d e l S e n s it iv it y ( 9 5 % C I) P S p e c if ic it y ( 9 5 % C I) p h e te r o g e n e it y , I 2 P * U lt r a s o n o g r a p h y P a ti e n t e n r o ll m e n t C o n se cu ti v e 3 0 .9 8 ( 0 .9 5 -1 .0 0 ) 0 .0 1 0 .9 0 ( 0 .7 7 -1 .0 0 ) 0 .5 5 4 3 .0 % 0 .1 8 C o n v e n ie n c e 6 0 .9 5 ( 0 .9 0 -0 .9 9 ) 0 .9 1 ( 0 .8 6 -0 .9 6 ) O p e r a to r E m e rg e n cy p h y si ci a n 3 0 .9 0 ( 0 .8 1 -0 .9 8 ) < 0 .0 0 1 0 .9 0 ( 0 .8 3 -0 .9 7 ) 0 .0 9 2 1 .0 % 0 .2 8 O th e r p h y si ci a n 6 0 .9 6 ( 0 .9 3 -0 .9 9 ) 0 .9 1 ( 0 .8 4 -0 .9 8 ) S a m p le s iz e < 1 0 0 6 0 .9 1 ( 0 .8 4 -0 .9 7 ) 0 .0 1 0 .9 0 ( 0 .8 3 -0 .9 7 ) 0 .0 4 1 2 .0 % 0 .3 2 ≥ 1 0 0 3 0 .9 7 ( 0 .9 4 -1 .0 0 ) 0 .9 3 ( 0 .8 7 -0 .9 8 ) F r e q u e n c y o f tr a n s d u c e r 5 -1 0 M H z 6 0 .9 4 ( 0 .8 9 -0 .9 9 ) 0 .6 2 0 .9 0 ( 0 .8 5 -0 .9 5 ) 0 .0 3 0 .0 % 0 .5 1 1 0 -1 5 M H z 3 0 .9 5 ( 0 .8 8 -1 .0 0 ) 0 .9 5 ( 0 .8 9 -1 .0 0 ) T y p e o f fr a c tu r e R ib 4 0 .9 7 ( 0 .9 3 -1 .0 0 ) 0 .0 1 0 .8 9 ( 0 .8 3 -0 .9 6 ) 0 .0 1 4 5 .0 % 0 .1 6 S te rn u m / C la v ic le 5 0 .9 1 ( 0 .8 4 -0 .9 7 ) 0 .9 3 ( 0 .9 4 -0 .9 8 ) R a d io g r a p h y P a ti e n t e n r o ll m e n t C o n se cu ti v e 7 0 .8 0 ( 0 .5 9 - 1 .0 0 ) 0 .7 0 1 .0 0 ( 1 .0 0 - 1 .0 0 ) 0 .9 9 0 .0 % 0 .7 0 C o n v e n ie n c e 5 0 .7 3 ( 0 .4 5 - 1 .0 0 ) 1 .0 0 ( 0 .9 8 - 1 .0 0 ) O p e r a to r E m e rg e n cy p h y si ci a n 3 0 .6 6 ( 0 .2 7 - 1 .0 0 ) 0 .5 3 1 .0 0 ( 1 .0 0 - 1 .0 0 ) 0 .9 9 0 .0 % 0 .7 8 O th e r p h y si ci a n 9 0 .8 0 ( 0 .6 3 - 0 .9 8 ) 1 .0 0 ( 1 .0 0 - 1 .0 0 ) S a m p le s iz e < 1 0 0 7 0 .7 3 ( 0 .4 9 - 0 .9 7 ) 0 .4 4 1 .0 0 ( 1 .0 0 - 1 .0 0 ) 0 .9 9 0 .0 % 0 .5 7 ≥ 1 0 0 5 0 .8 2 ( 0 .6 1 - 1 .0 0 ) 1 .0 0 ( 1 .0 0 - 1 .0 0 ) T y p e o f fr a c tu r e R ib 8 0 .7 7 ( 0 .5 7 - 0 .9 7 ) 0 .5 6 1 .0 0 ( 1 .0 0 - 1 .0 0 ) 0 .9 9 0 .0 % 0 .9 8 S te rn u m / C la v ic le 4 0 .7 7 ( 0 .4 8 - 1 .0 0 ) 1 .0 0 ( 1 .0 0 - 1 .0 0 ) *, P v a lu e < 0 .1 w a s co n si d e re d a s si g n if ic a n t fo r h e te ro g e n e it y ; C I: C o n fi d e n c e i n te rv a l. This open-access article distributed under the terms of the Creative Commons Attribution NonCommercial 3.0 License (CC BY-NC 3.0). Copyright © 2016 Shahid Beheshti University of Medical Sciences. All rights reserved. Downloaded from: www.jemerg.com Yousefifard et al 60 bone fractures following trauma was prominently higher than radiography (97% vs. 77%). Yet, the specificity of radiography was found to be significantly higher than ul- trasonography in this regard (100% vs. 94%). On this ba- sis and according to calculated likelihood ratios, a nega- tive result of ultrasonography in detection of thoracic fracture is more reliable than radiography (negative likelihood ratio=0.03), while a positive result of chest ra- diography is more reliable than ultrasonography (posi- tive likelihood ratio=774.63). Ultrasonography had a higher sensitivity in diagnosis of rib fractures rather than other chest wall bones, while the type of fracture had no effect on diagnostic value of radiography. This finding can be ascribed to the higher attention that physicians pay to rib fractures rather than other chest wall bones such as scapula and sternum. Fractures are diagnosed via ultrasonography based on observation of cortical bone disruption. In cases of small fractures, detection of this sign in sonogram and distin- guishing it from other findings is highly dependent on the skills of the operator. The role of operator’s skills in detection of injuries via ultrasonography was verified in the present study as well (31-34). Ultrasonography by a radiologist has a higher sensitivity compared to emer- gency medicine specialist. The present study found that the specificity of this modality increased with frequen- cies of higher than 10MHz which might be due to the higher resolution obtained with higher frequencies (35), making it easier to detect the signs of fracture. Some narrative review articles and qualitative system- atic reviews are indicative of the potential benefit of ul- trasonography in detection of chest wall fractures. In this regard, Chan, in his systematic review conducted on studies indexed in Medline, declares that ultrasonogra- phy has a higher sensitivity in detection of thoracic bone fractures compared to radiography (13). Finding the di- agnostic accuracy of ultrasonography to be two times the ability of radiography in fracture diagnosis, Dietrich et al. also referred to ultrasonography as a useful diagnostic tool for detection of rib fractures (36). The results of the present meta-analysis were congruent with these find- ings. Presence of considerable heterogeneity between the in- cluded articles and simultaneous inclusion of retrospec- tive and prospective studies in the meta-analysis were major limitations of this study. Subgroup analysis was performed to overcome the heterogeneity problem. Conclusion: Base on the findings of the present meta-analysis, screening performance characteristic of ultrasonogra- phy in detection of thoracic bone fractures was found to be higher than radiography. However, these characteris- tics were more prominent in detection of rib fractures and in cases where was performed by a radiologist. Acknowledgments: None Conflict of interest: None Funding support: This research has been supported by Tehran University of Medical Sciences & health Services grant number: 93- 02-38-25618. Authors’ contributions: All authors passed four criteria for authorship contribu- tion based on recommendations of the International Committee of Medical Journal Editors. References: 1. Hendrich C, Finkewitz U, Berner W. Diagnostic value of ultrasonography and conventional radiography for the assessment of sternal fractures. Injury. 1995;26(9):601-4. 2. Engin G, Yekeler E, Güloǧlu R, Acunaş B, Acunaş G. 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Lee JH, Jeong YK, Park KB, Park JK, Jeong AK, Hwang JC. Operator-dependent techniques for graded compression sonography to detect the appendix and diagnose acute appendicitis. Am J Roentgenol. 2005;184(1):91-7. 35. Majumdar S, Kumar PS, Pandit A. Effect of liquid-phase properties on ultrasound intensity and cavitational activity. Ultrason Sonochem. 1998;5(3):113-8. 36. Dietrich CF, Mathis G, Cui XW, Ignee A, Hocke M, Hirche TO. Ultrasound of the pleurae and lungs. Ultrasound Med Biol. 2015;41(2):351-65. This open-access article distributed under the terms of the Creative Commons Attribution NonCommercial 3.0 License (CC BY-NC 3.0). Copyright © 2016 Shahid Beheshti University of Medical Sciences. All rights reserved. Downloaded from: www.jemerg.com Yousefifard et al 62 A B Figure 2: Deeks’ funnel plot asymmetry test for assessment of publication bias. P values < 0.05 was considered as significant. Ultrasonography (A); Radiography (B). ESS: Effective sample sizes. A B Figure 3: Summary receiver operative curves (SROC) for ultrasound (A) and chest radiography (B) in detection of thoracic bone fractures. AUC: Area under the curve; SENS: Sensitivity; SPEC: Specificity. 1 2 3 4 5 6 7 8 9 .1 .15 .2 .25 1 / ro o t( E S S ) 1 10 100 1000 Diagnostic Odds Ratio Study Regression Line Deeks' Funnel Plot Asymmetry Test pvalue = 0.68 1 2 3 4 5 6 7 8 9 10 11 12 .05 .1 .15 .2 .25 1 / ro o t( E S S ) 1 10 100 1000 Diagnostic Odds Ratio Study Regression Line Deeks' Funnel Plot Asymmetry Test pvalue = 0.39 12 3 4 5 6 7 8 9 0.0 0.5 1.0 S e n si ti v it y 0.00.51.0 Specificity Observed Data Summary Operating Point SENS = 0.97 [0.90 - 0.99] SPEC = 0.94 [0.86 - 0.97] SROC Curve AUC = 0.99 [0.97 - 0.99] 95% Confidence Contour 95% Prediction Contour SROC with Prediction & Confidence Contours 1 2 3 4 5 6 7 8 9 10 11 12 0.0 0.5 1.0 S e n si ti v it y 0.00.51.0 Specificity Observed Data Summary Operating Point SENS = 0.77 [0.56 - 0.90] SPEC = 1.00 [0.91 - 1.00] SROC Curve AUC = 0.97 [0.96 - 0.99] 95% Confidence Contour 95% Prediction Contour SROC with Prediction & Confidence Contours This open-access article distributed under the terms of the Creative Commons Attribution NonCommercial 3.0 License (CC BY-NC 3.0). Copyright © 2016 Shahid Beheshti University of Medical Sciences. All rights reserved. Downloaded from: www.jemerg.com 63 Emergency (2016); 4 (2): 55-64 A B Figure 4: Forest plot of screening performance characteristics of chest ultrasonography in detection of thoracic bone fractures. Sensitivity and specificity (A); Diagnostic likelihood ratio (DLR) (B). CI: Confidence interval. SENSITIVITY (95% CI) Q = 71.95, df = 8.00, p = 0.00 I2 = 88.88 [82.99 - 94.77] 0.97[0.90 - 0.99] 1.00 [0.96 - 1.00] 1.00 [0.86 - 1.00] 0.93 [0.76 - 0.99] 0.95 [0.84 - 0.99] 1.00 [0.85 - 1.00] 0.80 [0.70 - 0.89] 0.93 [0.68 - 1.00] 0.89 [0.65 - 0.99] 1.00 [0.78 - 1.00]1.00 [0.78 - 1.00] Author / year COMBINED Uzun 2013 You 2010 Weinberg 2010 Cross 2010 Jin 2006 Rainer 2004 Hurley 2004 Engin 2000 Hendrich 1995 0.7 1.0 SPECIFICITY (95% CI) Q = 28.54, df = 8.00, p = 0.00 I2 = 71.97 [52.99 - 90.95] 0.94[0.86 - 0.97] 0.89 [0.52 - 1.00] 1.00 [0.74 - 1.00] 0.88 [0.80 - 0.94] 0.96 [0.88 - 1.00] 1.00 [0.79 - 1.00] 0.83 [0.52 - 0.98] 1.00 [0.48 - 1.00] 0.60 [0.15 - 0.95] 0.97 [0.83 - 1.00]0.97 [0.83 - 1.00] Author / year COMBINED Uzun 2013 You 2010 Weinberg 2010 Cross 2010 Jin 2006 Rainer 2004 Hurley 2004 Engin 2000 Hendrich 1995 0.1 1.0 DLR POSITIVE (95% CI) Q = 32.43, df = 8.00, p = 0.00 I2 = 59.14 [59.14 - 91.52] 16.26[6.80 - 38.87] 6.63 [1.52 - 29.00] 25.48 [1.68 - 386.24] 7.89 [4.59 - 13.56] 27.17 [6.95 - 106.19] 33.29 [2.17 - 511.15] 4.82 [1.35 - 17.15] 10.88 [0.76 - 155.24] 2.22 [0.75 - 6.58] 20.02 [4.19 - 95.62]20.02 [4.19 - 95.62] Author / year COMBINED Uzun 2013 You 2010 Weinberg 2010 Cross 2010 Jin 2006 Rainer 2004 Hurley 2004 Engin 2000 Hendrich 1995 0.8 511.2 DLR NEGATIVE (95% CI) Q = 60.44, df = 8.00, p = 0.00 I2 = 86.76 [79.40 - 94.13] 0.03[0.01 - 0.11] 0.01 [0.01 - 0.10] 0.02 [0.01 - 0.32] 0.08 [0.02 - 0.31] 0.05 [0.01 - 0.19] 0.02 [0.01 - 0.33] 0.24 [0.14 - 0.40] 0.10 [0.02 - 0.48] 0.19 [0.04 - 0.82] 0.03 [0.01 - 0.50]0.03 [0.01 - 0.50] Author / year COMBINED Uzun 2013 You 2010 Weinberg 2010 Cross 2010 Jin 2006 Rainer 2004 Hurley 2004 Engin 2000 Hendrich 1995 0 1 This open-access article distributed under the terms of the Creative Commons Attribution NonCommercial 3.0 License (CC BY-NC 3.0). Copyright © 2016 Shahid Beheshti University of Medical Sciences. All rights reserved. Downloaded from: www.jemerg.com Yousefifard et al 64 A B Figure 5: Forest plot of screening performance characteristics of chest radiography in detection of thoracic bone fractures. Sensi- tivity and specificity (A); Diagnostic likelihood ratio (DLR) (B). CI: Confidence interval. SENSITIVITY (95% CI) Q =438.10, df = 11.00, p = 0.00 I2 = 97.49 [96.76 - 98.21] 0.77[0.56 - 0.90] 0.65 [0.61 - 0.68] 0.47 [0.21 - 0.73] 1.00 [0.96 - 1.00] 0.49 [0.35 - 0.63] 0.47 [0.30 - 0.65] 0.81 [0.71 - 0.89] 0.34 [0.28 - 0.41] 0.60 [0.51 - 0.69] 0.69 [0.57 - 0.80] 1.00 [0.85 - 1.00] 0.80 [0.70 - 0.89] 0.93 [0.68 - 1.00]0.93 [0.68 - 1.00] Author / year COMBINED Park 2015 Hoffstetter 2014 Uzun 2013 Chardoli 2013 Blasinska 2013 Yazkan 2012 Szucs-Farkas 2011 Wootton 2008 Traub 2007 Jin 2006 Rainer 2004 Hurley 2004 0.2 1.0 SPECIFICITY (95% CI) Q =399.03, df = 11.00, p = 0.00 I2 = 97.24 [96.42 - 98.06] 1.00[0.91 - 1.00] 0.94 [0.90 - 0.96] 1.00 [0.86 - 1.00] 1.00 [0.63 - 1.00] 1.00 [0.98 - 1.00] 1.00 [0.87 - 1.00] 1.00 [0.96 - 1.00] 0.55 [0.38 - 0.71] 1.00 [0.96 - 1.00] 1.00 [0.96 - 1.00] 1.00 [0.79 - 1.00] 0.83 [0.52 - 0.98] 1.00 [0.48 - 1.00]1.00 [0.48 - 1.00] Author / year COMBINED Park 2015 Hoffstetter 2014 Uzun 2013 Chardoli 2013 Blasinska 2013 Yazkan 2012 Szucs-Farkas 2011 Wootton 2008 Traub 2007 Jin 2006 Rainer 2004 Hurley 2004 0.4 1.0 DLR POSITIVE (95% CI) Q =420.69, df = 11.00, p = 0.00 I2 = 96.62 [96.62 - 98.15] 774.63[7.00 - 85753.00] 10.50 [6.60 - 16.69] 23.44 [1.44 - 382.77] 17.90 [1.21 - 264.74] 147.12 [9.12 - 1000] 25.46 [1.60 - 405.59] 135.00 [8.50 - 1000] 0.76 [0.52 - 1.13] 114.43 [7.19 - 1000] 136.30 [8.55 - 1000] 33.29 [2.17 - 511.15] 4.82 [1.35 - 17.15] 10.88 [0.76 - 155.24]10.88 [0.76 - 155.24] Author / year COMBINED Park 2015 Hoffstetter 2014 Uzun 2013 Chardoli 2013 Blasinska 2013 Yazkan 2012 Szucs-Farkas 2011 Wootton 2008 Traub 2007 Jin 2006 Rainer 2004 Hurley 2004 0.5 85753.0 DLR NEGATIVE (95% CI) Q =359.29, df = 11.00, p = 0.00 I2 = 96.94 [96.00 - 97.88] 0.23[0.11 - 0.48] 0.37 [0.34 - 0.42] 0.54 [0.34 - 0.86] 0.01 [0.01 - 0.09] 0.51 [0.39 - 0.67] 0.54 [0.39 - 0.74] 0.20 [0.13 - 0.30] 1.19 [0.89 - 1.00] 0.40 [0.32 - 0.49] 0.31 [0.22 - 0.44] 0.02 [0.01 - 0.33] 0.24 [0.14 - 0.40] 0.10 [0.02 - 0.48]0.10 [0.02 - 0.48] Author / year COMBINED Park 2015 Hoffstetter 2014 Uzun 2013 Chardoli 2013 Blasinska 2013 Yazkan 2012 Szucs-Farkas 2011 Wootton 2008 Traub 2007 Jin 2006 Rainer 2004 Hurley 2004 0 1