Ali 2012.

Study characteristics
Patient sampling	Adult patients (> 18 years of age) undergoing elective surgeries requiring general anaesthesia with endotracheal intubations were enrolled
Patient characteristics and setting	Edentulous patients, those unable to open the mouth or with limited cervical movement or requiring rapid sequence induction were excluded Sample size: 324 199 females Mean age: 43 years
Index tests	MMT, ULBT
Target condition and reference standard(s)	Difficult laryngoscopy: laryngoscopy was done with Macintosh laryngoscope blade size 3 or 4, and laryngoscopic view of the first attempt at intubation was graded and recorded according to Cormack and Lehane classification with the patient in the sniffing position but without applying external laryngeal pressure
Flow and timing	Preoperatively; no further information
Comparative
Notes
Methodological quality
Item	Authors' judgement	Risk of bias	Applicability concerns
DOMAIN 1: Patient Selection
Was a consecutive or random sample of patients enrolled?
Was a case‐control design avoided?
Did the study avoid inappropriate exclusions?
DOMAIN 2: Index Test All Tests
Were the index test results interpreted without knowledge of the results of the reference standard?
If a threshold was used, was it pre‐specified?
Did the assessors of the index test have appropriate training?
Was interobserver variability reported for some or all patients?
Was interobserver agreement acceptable?
DOMAIN 3: Reference Standard
Is the reference standards likely to correctly classify the target condition?
Were the reference standard results interpreted without knowledge of the results of the index tests?
DOMAIN 4: Flow and Timing
Was there an appropriate interval between index test and reference standard?
Did all patients receive the same reference standard?
Were all patients included in the analysis?