Table 3

Estimated seasonal phase as calendar days and amplitude for cardiovascular disease risk factors, adjusted for sex and age, with median and IQR, and p value for test of seasonality at population and individual levels, the Tromsø Study 1979–2008

Variable (subjects/observations) unitsPhase, median (IQR; days)Amplitude, median (IQR)Population, p valueIndividual, p Value
SBP (37 998/91 739), mm HgMarch 27 (February 6 to April 25; 78)1.03 (0.64–1.80)<0.001<0.001
DBP (37 998/91 739), mm HgJanuary 14 (December 13 to February 2; 51)0.54 (0.39–0.84)<0.001<0.001
HR (34 680/74 998), bpmNovember 12 (October 11 to December 12; 62)0.72 (0.56–1.01)<0.001<0.001
Weight (37 918/84 545), kgJanuary 19 (December 25 to May 4; 130)0.54 (0.30–0.88)<0.001<0.001
Cholesterol (37 986/92 641), mmol/lNovember 27 (October 26 to December 23; 58)0.13 (0.10–0.19)<0.001<0.001
Triglycerides (37 982/92 626), %September 21 (August 25 to October 8; 44)3.0 (2.3–4.1)<0.001<0.001
HDL cholesterol (37 971/92 576), mmol/lDecember 10 (December 1 to December 19; 18)0.031 (0.029–0.037)<0.001<0.001
CRP (16 292/31 936), %May 23 (March 8 to August 5; 150)6.4 (3.3–11.2)0.131<0.001
CRP if CRP<10 mg/l (15 909/30 557), %June 18 (April 17 to September 19; 155)7.4 (3.9–12.1)0.131<0.001
Fibrinogen (16 450/25 421), g/lApril 29 (April 19 to May 7; 18)0.055 (0.050–0.063)<0.001<0.001
Fibrinogen if CRP <10 mg/l (13 884/16 816), g/lFebruary 22 (January 29 to May 20; 112)0.045 (0.027–0.079)0.005<0.001
  • CRP, C reactive protein; DBP, diastolic blood pressure; HDL, high-density lipoprotein; HR, heart rate; SBP, systolic blood pressure.