Parathyroid hormone plus alendronate in osteoporosis: a meta-analysis of randomized controlled trials

Parathyroid hormone (PTH) increases both bone formation (BMD) and bone resorption, whereas alendronate reduces bone resorption. It is possible that the combination therapy of PTH with alendronate will enhance their effects on BMD. Therefore, we conducted this meta-analysis to evaluate the efficacy of the combination therapy of PTH with alendronate in the treatment of patients with osteoporosis.

A comprehensive literature search of PubMed, Embase, and Web of Science was conducted to identify relative studies. Eligible studies were randomized controlled trials (RCT), which assessed the efficacy of combination therapy in patients with osteoporosis. The outcomes included the mean percent increases in BMD of lumbar spine, femoral neck, total hip, and distal radius. Weighted mean difference (WMD) with 95% confidence intervals (CIs) were calculated using of random-effects or fixed-effects model, depending on the heterogeneity between the included studies.

Six RCTs with a total number of 833 patients were included in this meta-analysis. The pooled estimates showed that, the combination therapy of PTH with alendronate resulted in a higher mean percent change of increased BMD in distal radius (WMD = 2.45, 95% CI: 1.58, 3.31; P = 0.000), but not in lumbar spine (WMD = -0.83, 95% CI: -3.48, 1.81; P = 0.538), femoral neck (WMD = -0.99, 95% CI: -2.04, 0.07; P = 0.068), and total hip (WMD = -0.06, 95% CI: -0.93, 0.81; P = 0.892). The subgroup analysis based on the dosage and schedule of PTH, study duration, gender of patients, and anabolic agents, were conducted. And results revealed that among the patients in the combination therapy group, greater increases in the spine BMD were observed when the PTH was administered with a dosage of 20 μg (WMD = 2.33, 95% CI: 1.24, 3.43; P = 0.000), or the treatment duration lasted more than 12 months (WMD = 2.23, 95% CI: 1.00, 3.47; P = 0.000), or the combination therapy was used in osteoporosis women (WMD = 1.58, 95% CI: 0.63, 2.53; P = 0.001). However, the combination of PTH of 40 μg with alendronate produced a decrease in the BMD at spine (WMD = -4.56, 95% CI: -7.56, -1.56; P = 0.003) and femoral neck (WMD = -5.82, 95% CI: -9.91, -1.72; P = 0.005).

Our findings indicated that the addition of alendronate to PTH in the treatment of osteoporosis, reduced the ability of PTH therapy to increase the BMD at the lumbar spine, femoral neck, and total hip.