We agree that a definitive conclusion about TCAs and their possible effects on change in bone mineral density cannot be made based on our analysis. As we discussed in our article,1 TCAs are often prescribed for indications other than depression and, when prescribed for conditions such as insomnia or chronic pain, are often prescribed at low doses. Type II error is certainly possible, given our smaller number of TCA users. Based on our number of TCA users and nonusers and the standard deviation for their rates of bone loss, we had 80% power to detect a difference of 0.35 in the means of the annualized percentage change in total hip bone mineral density.
Diem S, Blackwell T, Stone KL, Yaffe K, Haney E, Bliziotes M, Ensrud KE. Concerns About Bone Safety of Tricyclic Antidepressant Therapy—Reply. Arch Intern Med. 2008;168(4):436. doi:10.1001/archinternmed.2007.115