Spousal concordance has already been observed for several other diseases but it has not yet been studied for bone loss. Our aim was to determine whether or not bone changes were the same within spouses who have shared the same environment for many decades.

We conducted a prospective study on an average of 5±3years in a single center. We evaluated in the 104 spouses who came at least twice and had more than 1year of follow-up the changes in bone mineral density (BMD) at femoral neck adjusted on weight and height, and on hormone replacement therapy use and duration for women. Lifestyle characteristics and biological parameters were evaluated at baseline.

The mean (±SD) baseline age of wives was 63±5years and that of their husbands was 66±5years. They had been living together for 40±8years. Most of the environmental baseline factors were correlated within partners: BMI (r=0.26, P<0.01), 25-OHD₃ (r=0.32, P<0.01), daily calories (r=0.52, P<0.001) and calcium intake (r=0.31, P<0.01), physical activity (r=0.43, P<0.0001). Bone loss was observed in wives (−0.0023g/cm²/yr, P<0.01) but not in their husbands (0.0016g/cm²/yr, P=0.10). Changes of BMD were not correlated within spouses (r=0.0004, P=0.99). In women, 25-OHD₃ and interactions of tobacco with 25-OHD₃ and calories intake explained 37% of the bone loss variance (P<0.01).

Environmental factors do not appear to influence changes in bone density in the same manner in subjects of different genders.