Comparison of Positive Predictive value of Mallampati Test and Upper lip Bite test in Association with difficult intubation
Keywords:
Upper Lip Bite Test, Modified Mallampati Classification, Difficult Intubation, Predictive Value, ROC curveAbstract
Background: The upper lip bite test and Modified Mallampati Test are common bed side screening test used to assess patient airway pre-operatively for possible difficult intubation, and guides anesthesiologists for better planning of airway management. For this sole purpose the evaluation of Positive predictive value and Comparison of both are essential and paramount for evidence-based airway assessment and management.
Objective: The study compares the Predictive performance of ULBT and MMT for Difficult Intubation in patients undergoing general Anesthesia.
Methods: This was an observational study where both test were performed on 179 patients at Lady Reading Hospital, Peshawar. The primary outcome was difficult Intubation, defined as, more attempts required for intubation, takes more time than 10 seconds, and used advanced equipment for intubating the patient. Association was analyzed for ULBT and MMT against difficult intubation via Chi Square at alpha level of 0.05, Predictive accuracy was analyzed via Receiver Operating Curve (ROC), predictive values (PPV) were manually calculated for each class of the ULBT and MMT.
Results: The incidence of difficult Intubation in the study was 7.8% (n=14), with statistically significant association of ULBT and MMT with difficult intubation (ULBT X2=25.09, p<0.001; MMT X2=32.78, p<0.001). The PPV for ULBT class III was 45.5% (n=5/11) and for MMT class IV it was 75% (n=3/4), MMC class III had 17.1% of PPV. As per ROC analysis, there was moderate and comparable diagnostic accuracy, ULBT Area under the Curve (AUC): 0.749 and MMT AUC: 0.755.
Conclusion: Both these tests’ higher classifications are significantly associated with difficult intubation, MMC had highest single class (MMT Class IV) PPV, while ULBT had absolute greater number of difficult cases. The moderate AUC supports multimodal or multi-parameter approach as no single standalone test is highly reliable.
