Table 1.

Differences between patients with and without headache

Variable	Entire study sample (n = 7832)	Patients without headache (n = 2557)	Patients with headache (n = 5275)	P value
Female sex	3856 (49.2%)	1221 (47.8%)	2635 (50.0%)	0.068
Cardiovascular disorders	193 (2.5%)	64 (2.5%)	129 (2.4%)	0.878
Diabetes	211 (2.7%)	41 (1.6%)	170 (3.2%)	< 0.001
COPD	79 (1.0%)	17 (0.7%)	62 (1.2%)	0.034
Cancer	65 (0.8%)	16 (0.6%)	49 (0.9%)	0.165
Kidney disorders	21 (0.3%)	3 (0.1%)	18 (0.3%)	0.072
Hepatic disorders	14 (0.2%)	4 (0.2%)	10 (0.2%)	0.745
Obesity	67 (0.9%)	15 (0.6%)	52 (1.0%)	0.072
Vaccination	337 (4.3%)	112 (4.4%)	225 (4.3%)	0.814
Onset within 48 h	4573 (58.4%)	1398 (54.7%)	3175 (60.2%)	< 0.001
Epidemiological contact	2964 (37.8%)	884 (34.6%)	2080 (39.4%)	< 0.001
Sudden onset	7325 (93.5%)	2308 (90.3%)	5017 (95.1%)	< 0.001
Fever	7427 (94.8%)	2361 (92.3%)	5066 (96.0%)	< 0.001
Shivering	5129 (65.5%)	1188 (46.5%)	3941 (74.7%)	< 0.001
Asthenia	6009 (76.7%)	1548 (60.5%)	4461 (84.6%)	< 0.001
Myalgia	5248 (67.0%)	1158 (45.3%)	4090 (77.5%)	< 0.001
Cough	6695 (85.5%)	2135 (83.5%)	4560 (86.4%)	0.001
Dyspnea	736 (9.4%)	208 (8.1%)	528 (10.0%)	0.008
Nasopharyngeal erythema	6838 (87.3%)	2128 (83.2%)	4710 (89.3%)	< 0.001
Gastrointestinal symptoms	2123 (27.1%)	628 (24.6%)	1495 (28.3%)	< 0.001
Oropharyngeal swab obtention	2113 (27.0%)	668 (26.1%)	1445 (27.4%)	0.235
Confirmed infection	1194/2113 (56.5%)	376/668 (56.3%)	818/1445 (56.6%)	0.985
A subtype	809/1194 (67.8%)	257/376 (68.4%)	552/818 (67.5%)	0.764
B subtype	385/1194 (32.2%)	119/376 (31.6%)	266/818 (32.5%)	0.823
Hospital referral	49 (0.6%)	25 (1.0%)	24 (0.5%)	0.006
Scholar absenteeism	2205/6624 (33.3%)	765/2315 (33.0%)	1440/4309 (33.4%)	0.759
Medical leave	591 (7.5%)	120 (4.7%)	471 (8.9%)	< 0.001

COPD Chronic obstructive pulmonary disease. Differing denominators indicate subgroup analyses