Parameter estimates for the course of decline of per cent predicted forced vital capacity from time of initiation of noninvasive ventilation (Model 2)

ParameterOverall cohortAdherent patientsNonadherent patientsp-value#
Mean (se)95% CIMean (se)95% CIMean (se)95% CI
b1 %74.0 (1.2)71.1, 76.472.2 (1.5)69.3, 75.176.1 (1.6)72.8, 79.30.081
b2 %−33.4 (1.7)−36.7, −30.1−30.3 (1.9)−34.1, −26.5−35.8 (2.5)−40.8, 30.70.091
b3 months−5.2 (0.5)−6.2, −4.3−4.3 (0.5)−5.3, 3.3−6.7 (0.9)−8.4, −5.00.017
b4 months3.1 (0.4)2.4, 3.92.3 (0.4)1.4, 3.13.8 (0.6)2.6, 5.00.036
b1+b2 %40.6 (2.1)34.7, 43.041.9 (1.1)39.7, 44.138.5 (2.1)34.4, 42.70.16

b1: per cent predicted vital capacity before onset of decline of lung function; b2: magnitude of decline in predicted forced vital capacity to the lower asymptote, represented in the model as a negative number such that b1+b2 is the final per cent predicted vital capacity; b3: time (months) from initiation of noninvasive ventilation to the midpoint between the two asymptotes, also representing the inflection point of the forced vital capacity time-course curve (a negative number as the inflection occurred before initiation of noninvasive ventilation); b4: a timescale factor (months) that reflects the rapidity of decline of forced vital capacity, such that a smaller b4 reflects a more rapid decline.

#: difference between adherent and nonadherent patients; significance set at p<0.05.

: p<0.001 for all parameter estimates, indicating that all four parameters contributed significantly to the per cent predicted forced vital capacity.