text: 1.011; P < .001 for general practitioner visits; OR, 1.015; 
  P < .001 for emergency department visits; and OR, 
  1.023, P ¼ .005 for hospitalization for respiratory illness) 
  (Table 8).  productivity loss (coefﬁcient, 0.383; P < .001), and 
  greater activity impairment (coefﬁcient, 0.501; P < .001), 
  as measured by the Work Productivity and Activity 
  Impairment questionnaire21 (Table 9). 