Introduction/Aim: Decline in lung function variables have been shown to be associated with adverse clinical outcomes in motor neuron disease (MND). We compared sniff nasal inspiratory pressure (SNIP) and positional forced vital capacity (FVC) in their ability to predict clinical outcomes in MND. SNIP, compared to positional FVC, may be a more pragmatic test in MND patients with significant bulbar involvement.

Methods: We retrospectively reviewed MND patients who attended our MND clinic from first January 2009 to 3first December 2018. Their clinical progress was followed until 3first December 2019. Demographics and lung function variables including SNIP, spirometry with positional FVC were recorded. ANOVA and binary logistic progression models were used to evaluate for associations between SNIP and positional FVC and the following clinical outcomes: NIV initiation, twelve-month NIV initiation rate, twelve-month mortality rate, twelve-month hospitalization rate and median time to death. IBM SPSS (version 26) was used to conduct statistical analysis.

Results: 60 patients (38 males, 22 females) attended our clinic during the study period. The median age of patients was 63 years old, with 13 patients requiring PEG and 23 patients requiring NIV during the study period. 20 patients died during the study period. Mean 12-month hospitalization rate was 0.83 admissions/year and 6 patients died within 12 months of entering the study period. ANOVA revealed a significant trend of positional FVC but not SNIP in predicting NIV initiation (F(1,58)=11.27, p<0.001), 12-month NIV initiation rate (F(1,21)=9.184, p<0.006) and overall mortality (F(1,58)=9.68, p<0.003). Positional FVC but not SNIP appeared to be associated with statistically significant increased odds ratios regarding NIV initiation (OR=1.139, p=0.011) and mortality (OR=1.107, p=0.028) for study duration.

Conclusion: Positional FVC drop but not a reduced SNIP was statistically significantly associated with NIV initiation, overall mortality and 12-month mortality rates.