Meta-analysis on the diagnostic value of laser Doppler imaging for burn depth

Objective To evaluate the value of laser Doppler imaging (LDI) in diagnosing deep or superficial partial-thickness burn wound with meta-analysis. Methods Databases including PubMed, Cochrane Library were searched using key words " burn, burns, burn depth, laser Doppler imaging, laser Doppler perfusion imaging, LDI, LDPI" , and Chinese Journals Full-text Database, Wanfang Database, VIP Database were searched using Chinese key words "烧伤,烧伤深度,激光多普勒,激光多普勒血流灌注成像,激光多普勒成像仪" to obtain the published trials of LDI in diagnosing deep or superficial partial-thickness burn wound from the establishment of each database to October 2015. The risk of bias and applicability concerns of the included studies were evaluated by Quality Assessment of Diagnostic Accuracy Studies-2. Data were processed with Meta-DiSc 1.4 statistical software. The heterogeneity among the included studies was evaluated. The pooled estimates of LDI in diagnosing deep or superficial partial-thickness burn wound in the included studies, including sensitivity, specificity, positive likelihood ratio, negative likelihood ratio, diagnostic odds ratio, as well as the area under the curve of summary receiver operating characteristic and index of Q^* were calculated. The stability of results of the overall pooled estimates of the included studies was validated by sensitivity analysis. The sources of heterogeneity among the included studies were sought through subgroup analysis. The publication bias caused by the results of the included studies was evaluated by drawing the Deek′s funnel plot. Results A total of 5 articles conforming to the inclusion criteria, involving 138 patients and 179 burn wounds, were included. One of the included studies had low risk of bias, while the other 4 studies had high/unclear risk of bias. In applicability concern aspect, one of the included studies had high/unclear concerns regarding applicability, while the other 4 studies had low concerns regarding applicability. There was no heterogeneity caused by threshold effects among the included studies (no " shoulder arm" plot of the scattered-point distribution was observed in the space of the receiver operating characteristic, β^s=0.01, P>0.05). There was a high heterogeneity caused by non-threshold effects among the included studies (sensitivity I²=54%). The overall pooled sensitivity, specificity, positive likelihood ratio, negative likelihood ratio, and diagnostic odds ratio of the included studies on LDI in diagnosing deep or superficial partial-thickness burn wound were 95% (with 95% confidence interval 88%-99%), 96% (with 95% confidence interval 90%-99%), 9.75 (with 95% confidence interval 4.35-21.81), 0.11 (with 95% confidence interval 0.05-0.22), and 257.93 (with 95% confidence interval 58.96-1 128.41), respectively. The area under the curve of summary receiver operating characteristic was 0.98, with index of Q^* 94%. The results of the overall pooled estimates of the included studies was stable. The risk of bias of the selection of the patients, equipment type of LDI, and the selection of diagnostic method in control might be sources of the heterogeneity of the included studies. The Deek′s funnel plot indicated that there was no publication bias caused by the results of the included studies (P>0.05). Conclusions LDI has high sensitivity, specificity, positive likelihood ratio, diagnostic odds ratio and index of Q^*, large area under the curve of summary receiver operating characteristics, and low negative likelihood ratio in diagnosing deep or superficial partial-thickness burn wound, which has relatively high diagnostic value.