Objective: Genetic factors are known to affect blood pressure. A positive family history of hypertension is associated with higher blood pressure levels than a negative history. To our knowledge, there are no population-based data across linguistic regions on this topic in Switzerland. Furthermore, little is known about the association of family history of hypertension with dietary patterns. We analysed the association of father's, mother's and siblings' history of hypertension with blood pressure and dietary habits in the Swiss Survey on Salt Intake.
Methods: We used data from 1448 participants to the Swiss Survey on Salt intake, a population-based study conducted in 2010-2012 in the general population aged 15 years and older. Participants were asked about their family history of hypertension, their behaviour and perception in relation to dietary salt consumption, their lifestyle. Office blood pressure was measured using a validated automatic device. We estimated salt, potassium and protein intakes using 24-hour urinary sodium, potassium and urea excretions. We used multiple logistic and linear regressions to explore factors associated with family history of hypertension and the association of blood pressure with a family history of hypertension.
Results: The 785 men and 863 women had mean[SD] age of 48.3[18.6] and 46.6[18.2] years and bmi of 26.1[4.3] and 24.4[4.8] , respectively. Systolic/diastolic blood pressure (mm Hg) was higher in people with a positive as compared to those with a negative family history of hypertension (133.4/79.0 vs 127.4/74.4 in men and 120.8/73.4 vs 117.2/71.2 in women, all P<0.0001). In adjusted analyses, a positive family history of hypertension was associated with 3.8/3.9 mm Hg higher SBP/DBP in men (P<0.001), whereas no association persisted in women. In adjusted analyses, we found no significant differences in urinary sodium, potassium and urea excretions by family history of hypertension. People with a positive family history of hypertension, as compared to those with a negative history, tended to report more frequently to pay attention to their salt consumption (Odds ratio[Standard error] (OR[SE])=1.49[0.29] in women, P=0.04 and 1.45[0.31] in men, P=0.09). We found no association between family history of hypertension and self-reported attempt to limit salt intake. People from the German-speaking region had higher odds of a positive family history of hypertension than people from the French-speaking region (OR[SE]=1.81[0.39] in men, P=0.01 and 1.56[0.30] in women, P=0.02), independently of hypertension status.
Conclusions: We found a positive family history of hypertension to be associated with higher blood pressure in this Swiss population-based sample. People with a positive family
history of hypertension reported to pay more attention to dietary salt intake, although they did not attempt to limit salt intake. This was confirmed by the fact that we found similar dietary salt intake, estimated from 24-hour urinary sodium excretion, in people with and without family history of hypertension. We found no difference in 24-hour urinary potassium and urea excretions in people with and without family history of hypertension. Finally, we found higher prevalence of positive family history of hypertension in the German speaking region of Switzerland as compared to the French-speaking region, independently of hypertension status. Family history of hypertension does not appear to greatly influence dietary patterns in Switzerland.