A new, randomized, placebo-controlled trial studied the association between treatment with 250,000 IU cholecalciferol for 4 months following hip fracture surgery and incidence of falls. Results showed that at month 4 after surgery, 7 (6.3%) patients in the treatment group reported 1 falls compared to 23 (21.2%) in the placebo group (p 1 falls during the first 4 months of therapy?

Question

A new, randomized, placebo-controlled trial studied the association between treatment with 250,000 IU cholecalciferol for 4 months following hip fracture surgery and incidence of falls.  Results showed that at month 4 after surgery, 7 (6.3%) patients in the treatment group reported >1 falls compared to 23 (21.2%) in the placebo group (p < 0.01); there was a relative risk reduction of 70.3%.  Treatment with 250,000 IU cholecalciferol for 4 months costs $100 per patient.  Based on this information, how much would it cost to treat enough patients after hip surgery with 250,000 IU cholecalciferol to prevent >1 falls during the first 4 months of therapy?

Quizplus · Accepted Answer

Explanation: 11ec2b69_bdf8_2813_8f63_8f759b6dce1c_MD0005_00 The number needed to treat (NNT) represents the number of patients who need to be treated (eg, with 250,000 IU cholecalciferol) to prevent 1 bad outcome (eg, >1 falls), assuming the treatment is beneficial. NNT is the inverse of the absolute risk reduction (ARR), or 1 / ARR. ARR is calculated by subtracting the experimental event rate (EER) from the control event rate (CER): ARR = CER − EER In this case, CER is the proportion of patients who reported >1 falls in the placebo (control) group (ie, 21.2%), and EER is the proportion of patients who reported >1 falls in the 250,000 IU cholecalciferol treatment (experimental) group (ie, 6.3%). Therefore, ARR can be calculated as follows: ARR = (21.2 / 100) − (6.3 / 100) = (14.9 / 100) (ie, 0.212 − 0.063 = 0.149) Using this information, NNT is estimated by calculating the inverse of ARR: NNT = (1 / ARR) = (100 / 14.9) = 6.71 (ie, 1 / 0.149 = 6.71) Therefore, 6.71 patients with the condition (eg, recent surgical repair of a hip fracture) would have to be treated (eg, 250,000 IU cholecalciferol for 4 months after hip fracture surgery) to prevent 1 bad outcome (eg, >1 falls). Therefore, the cost would be: 6.71 patients × $100/patient = $671 (Choice A) NNT is the inverse of ARR, not the inverse of the relative risk reduction (1 / 0.703 = 1.42). Educational objective: The number needed to treat (NNT) is the number of patients who need to be treated to prevent an adverse event. It is a useful measure for evaluating the efficacy of a given therapy. NNT is calculated as the inverse of the absolute risk reduction (ARR); in other words, NNT = 1 / ARR.

A New, Randomized, Placebo-Controlled Trial Studied the Association Between Treatment