Associations between Unconventional Natural Gas Development and Nasal and Sinus, Migraine Headache, and Fatigue Symptoms in Pennsylvania

http://dx.doi.org/10.1289/EHP281



Table 1. Comparison of selected characteristics in survey responders and nonresponders.
Characteristic Responders (n = 7,785) Nonresponders (n = 15,525) p-Value
Notes: NA, not applicable; sd, standard deviation; UNGD, unconventional natural gas development.
Patients who lived outside Pennsylvania were excluded (n = 390). UNGD activity was averaged over 90 days before the survey.
ap-Value computed using Student’s t-test.
bp-Value computed using Chi-squared test.
cWithin responders and nonresponders separately, p-values were computed with one-way analysis of variance (ANOVA) to compare mean Charlson index across quartiles of UNGD.
Continuous composite UNGD activity metric, mean ± sd –0.02 ± 1.80 0.01 ± 2.78 0.26a
UNGD activity, n (%)
Quartile 1 2,052 (26.4) 3,775 (24.3) < 0.001b
Quartile 2 1,828 (23.5) 3,996 (25.7)
Quartile 3 2,017 (25.9) 3,814 (24.6)
Quartile 4 1,888 (24.3) 3,940 (25.4)
Charlson index, mean ± sd 3.43 ± 2.76 2.52 ± 2.65 < 0.001a
Charlson index stratified by quartiles of UNGD activity, mean ± sd
Quartile 1 3.27 ± 2.61 2.46 ± 2.46
Quartile 2 3.37 ± 2.71 2.48 ± 2.57 NA
Quartile 3 3.61 ± 2.83 2.68 ± 2.85
Quartile 4 3.47 ± 2.86 2.48 ± 2.70
p < 0.001c p < 0.001c