Short-Term Impact of Staying Home on Bone Health in Patients With Osteoporosis During a State of Emergency Declaration Due to COVID-19 in Kanagawa, Japan

Background On April 16, 2020, the Japanese government declared a state of emergency due to the spread of COVID-19 infection, leading prefectural governors to announce a stay-at-home order for 39 days until May 25, 2020. As physical inactivity is a risk factor for osteoporosis, we investigated the short-term impact of the stay-at-home order on bone health among patients with osteoporosis in our hospital in Kanagawa prefecture. Methods Thirty patients with osteoporosis with no delays in their regular medication who received care at our hospital's osteoporosis outpatient clinic within one month after the end of the state of emergency were included. Lumbar spine and femur proximal bone mineral density (BMD) were measured at the last follow-up date (May 25 to June 30, 2020; 0M) and six (6M) and 12 months (12M) before the last follow-up using dual-energy X-ray absorptiometry. Bone alkaline phosphatase (BAP), Tartrate-resistant Acid Phosphatase 5b (TRACP5b), calcium and phosphorus were assessed at the same time points. Results Serum BAP concentrations were significantly lower at 0M than 12M (p=0.040), but were comparable between 0M and 6M (p=0.527). Serum TRACP5b was significantly lower at 6M than 12M (p=0.009), but was similar between 0M and 6M (p=1.000). Serum calcium and phosphorus did not differ among the time points (p=0.516 and p=0.358, respectively). Similarly, lumbar spine and femoral neck BMD were comparable (p=0.679 and p=0.076, respectively). Conclusion Bone health in patients with osteoporosis was maintained during the short-term COVID-19 stay-at-home order among patients who experienced no delays in medication. However, larger and long-term studies are needed.