Predictive performance of thyromental height for difficult laryngoscopies in adults: a systematic review and meta-analysis

Use of the Thyromental Height Test for Prediction of Difficult Laryngoscopy: A Systematic Review and Meta-Analysis

“…The meta-analysis conducted by Carvalho et al [ 21 ] in 2021 reported similar but somewhat limited results. In their analysis, summary sensitivity and specificity for studies with a common threshold were 82.6% (95% CI, 74–88.8%) and 93.5% (95% CI, 79–98.2%), respectively [ 21 ]. Obviously, there are numeral differences in both sensitivity and specificity between their analyses and ours.…”

“…However, what needs to be kept in mind is the significant enlargement for the number of studies and total sample size/range included in our analysis. A total of 23 studies with 5896 patients were included, almost doubling the sample size, compared to 8 studies with 2844 patients as reported by Carvalho et al [ 21 ]; especially, three of the most recent studies [ 22 , 25 , 26 ], which are all included, are aimed at the predictive performance of TMHT for DL in specific populations with risk factors of difficult airways, such as obesity, an age over 65 years, and others. Knowing that these factors are directly associated with the prevalence of DL and were considered as exclusion criteria in Carvalho et al’s [ 21 ] work, the current study faces an extra challenge in the process of analysis and gains an extra validity in the results.…”

“…A total of 23 studies with 5896 patients were included, almost doubling the sample size, compared to 8 studies with 2844 patients as reported by Carvalho et al [ 21 ]; especially, three of the most recent studies [ 22 , 25 , 26 ], which are all included, are aimed at the predictive performance of TMHT for DL in specific populations with risk factors of difficult airways, such as obesity, an age over 65 years, and others. Knowing that these factors are directly associated with the prevalence of DL and were considered as exclusion criteria in Carvalho et al’s [ 21 ] work, the current study faces an extra challenge in the process of analysis and gains an extra validity in the results. Eight studies [ 20 , 33 , 34 , 35 , 36 , 37 , 38 , 39 ] conducted on the Chinese and Nepalese populations were included in our analysis, contributing to the ethnic diversity of patients.…”

“…Subsequently, several studies evaluated the actual performance of TMHT as a single predictor for DL in different populations [ 11 , 12 , 13 , 14 , 15 , 16 , 17 , 18 , 19 , 20 ]. In 2021, moreover, Carvalho et al [ 21 ] performed a meta-analysis that included eight studies and showed that TMHT was a good predictor of DL with a better performance than most previously reported bedside airway assessment tests. In the meta-analysis of Carvalho et al [ 21 ], however, exclusion of non-English language studies may have resulted in the absence of some important studies.…”

“…In 2021, moreover, Carvalho et al [ 21 ] performed a meta-analysis that included eight studies and showed that TMHT was a good predictor of DL with a better performance than most previously reported bedside airway assessment tests. In the meta-analysis of Carvalho et al [ 21 ], however, exclusion of non-English language studies may have resulted in the absence of some important studies. Most importantly, several new works assessing the performance of TMHT for prediction of DL have been published after their meta-analysis [ 22 , 23 , 24 , 25 , 26 , 27 ].…”