Effect of Parathyroid Hormone (1-34) on Fractures and Bone Mineral Density in Postmenopausal Women with Osteoporosis Elise Miller
Variables of Interest • Since we are dealing with Chi-square, there are 2 categorical variables. • Women were placed into 3 groups: • 1.)Placebo • N=544 • 2.)PTH 20-µg • N=541 • 3.)PTH 40-µg • N=552
Variables of Interest cont. • The second variable was whether or not new nonvertebral fractures had developed since the baseline examinations. • Or whether or not new fragility fractures developed.
To Compare the P-Values… • Placebo and Treatment were taken as the explanatory variables. • Whether there were new fractures was used as the response variable.
Minitab Procedure • For example: • Placebo: N=544 • Fracture= 53 • No Fracture= 491 • PTH 20: N=541 • Fracture=34 • No Fracture= 507 These numbers get inputted into MiniTab to find the P-value.
MiniTab Output C1 C2 Total 1 53 491 544 43.62 500.38 2.017 0.176 2 34 507 541 43.38 497.62 2.028 0.177 Total 87 998 1085 Chi-Sq = 4.398, DF = 1, P-Value = 0.036
Procedure cont. • The same procedure was done comparing each dose for total fracture and fragility fracture.
P-Values • Placebo vs. 20µg (Fracture) • By hand: p=.036 • Given: p=.04 • Placebo vs. 40µg (Fracture) • By hand: p=.015 • Given: p=.02 • Placebo vs. 20µg (Fragility) • By hand: p=.015 • Given: p=.02 • Placebo vs. 40µg (Fragility) • By hand: p=.012 • Given: p=.01
Consequences of Error • Type 1: • Researchers would give out a drug that doesn’t have any benefit to eliminating fracture. • Type 2: • The PTH would be considered ineffective and would not make it to the market.
Adverse Effects • No significant differences among the three groups regarding death. • Because the null states that both treatment and placebo have the same risk factors….. Would the null be accepted or rejected? • Regarding death, the null would be accepted because there was not significant difference between treatment and placebo.
What if researchers were wrong? • What type of error would be committed? • Type I: • This error would mean that treatment actually has risk of death.
Potential Bias • Like most medical research, bias is considered and ultimately eliminated. • People had to meet certain criteria in order to participate.
Research Conclusions • Treatment of postmenopausal osteoporosis with parathyroid hormone (1-34) decreases the risk of fracture. • Increases total-body bone mineral density. • In order to have minimal side effects, with higher bone density results and minimal fracture, the 20µg dose is the most beneficial.