Would you switch a patient with glucocorticoid induced osteoporosis to romosozumab if a patient sustained a fragility fracture 1 year into treatment with teriparatide?

This is an interesting question for which there is no evidence-based medicine. It would be important to know what bone was broken. If it was a vertebral fracture I would likely suggest a change to romosozumab because vertebral fractures are usually not traumatic and are the purest osteoporotic fracture (indicating compromised bone strength) because of the lack of trauma. That being said, vertebral fractures occur with all bone-strengthening medications, but with less frequency with our anabolic drugs. The issue of nonvertebral fractures including hip and non-hip, non-vertebral fractures is (in my opinion) different than vertebral fractures that occur when a patient is using bone-strengthening medication. Most non-vertebral fractures have an element of trauma associated with them and the force of that trauma is clearly critical, but unfortunately cannot be quantified. The efficacy of our bone-strengthening medications in preventing fragility fractures decreases from vertebral fractures (60-80% relative risk reduction) to hip fractures (30-40% relative risk reduction) to non-hip, non-vertebral fractures (20-30% relative risk reduction). Labeling a fragility fracture as a consequence of "drug inadequacy or drug failure" presupposes that another drug would have been more effective in preventing that fracture, but that in the absence of data, this is only speculation. If your patient has had improvement in their bone density and the fragility fracture was a consequence of a traumatic event such as a fall then the decision to switch from teriparatide to romosozumab would be taken with the hope that the latter is more effective than the former drug. The temptation to make that switch is great not the least of which because patients might wonder how effective a drug is when they experienced a fracture while taking that drug. Often the patient's query about drug efficacy can drive us to try another drug and for patients with osteoporosis, that decision is generally reasonable.