Fracture risk and fracture prevalence in women from outpatient osteoporosis clinic and subjects from population-based sample: A comparison between GO Study and RAC-OST-POL cohorts

Background. The method of recruiting the study subjects is an important element of the study design. It can have a strong influence on the results. Different recruitment schedules can give a different picture of the studied phenomenon. Objectives. The aim of the study was to compare bone health in a group of female patients treated for osteoporosis with a population-based sample. Materials and methods. A cohort of women from GO Study from 1 outpatient osteoporotic clinic (n = 1442, mean age 65.8 +/- 6.7 years) and population-based female sample of RAC-OST-POL Study (n = 963, mean age 65.8 +/- 7.5 years) were studied. Mean age did not differ between groups. Mean weight, height and body mass index (BMI) in subjects from GO Study and RAC- OST- POL Study were 69.5 +/- 13.1 kg, 157.8 +/- 6.1 cm and 27.9 +/- 5.1 kg/m(2), and 74.2 +/- 13.7 kg, 156.0 +/- 6.0 cm and 30.5 +/- 5.4 kg/m(2), respectively, and differed significantly (p < 0.0001 for each variable). Data on clinical risk factors for osteoporosis and fractures were collected. Bone densitometry at hip was performed using a Prodigy or Lunar DPX device (GE Healthcare, Waukesha, USA). Fracture risk was established using FRAX, Garvan and POL- RISK. Results. Mean values of T-score for femoral neck in subjects from GO Study and RAC-OST-POL Study were -1.67 +/- 0.91 and -1.27 +/- 0.91 and differed significantly (p < 0.0001). In GO Study and RAC-OST- POL Study, there were 518 (35.9%) and 280 (29.1%) subjects with fractures, respectively. The fracture frequency was significantly higher in the GO Study group (p < 0.001). Among clinical risk factors, only rheumatoid arthritis (p < 0.0001) secondary osteoporosis (p < 0.0001) and falls (p < 0.0001) were more frequent in RAC-OST-POL Study. Fracture risk established using FRAX, Garvan and POL-RISK calculators was significantly greater in patients enrolled in the GO Study than in subjects from the RAC-OST-POL population-based sample (p < 0.0001 for each variable). Conclusions. Differences noted between female patients treated for osteoporosis and population-based sample, especially in regard to fracture risk, reveal a strong influence of recruitment criteria on study results in the field of bone health and osteoporosis.