A Clinical Study on the Effect of Discontinuing Alendronate in Postmenopausal Women With Osteoporosis After a Treatment Period Without Fractures

Changes in bone mineral density (BMD)

Changes in lumbar spine and total hip BMD measured by dual energy X-ray arbsorptiometry. The three follow-up scans will be analyzed by a technician blinded to participant allocation, ie this person will not meet the patient and the patient will not be able see the results of the scans until the final study visit.

Time frame: Baseline, 12, 24 and 36 months

Bone turn over marker (CTX)

Fasting blood samples will be performed during the study period to analyze changes in carboxy-terminal collagen crosslinks (CTX).

Time frame: Blood samples are performed at baseline, 6, 12, 18, 24, and 36 months.

Bone turn over marker (P1NP)

Fasting blood samples will be performed during the study period to analyze changes in procollagen type I N-terminal propeptide (PINP).

Time frame: Blood samples are performed at baseline, 6, 12, 18, 24, and 36 months.

Restart Criteria

The proportion of participants meeting restart criteria during the study period. Restart criteria is defined as: Participants experiencing boneloss exceeding 10% from baseline in any region, one clinical vertebral fracture, two low energy fractures (including morphometric vertebral fracture but excluding fractures of scull, fingers or toes) are withdrawn from the study and offered treatment with alendronate or zoledronic acid after new diagnostic work-up.

Time frame: From enrollment to the end of the study period at 3 years

Adverse Events

At baseline a thoroughly physical examination of the participants and questioning concerning any conditions or diseases will take place. This way the investigators will be able to evaluate possible changes throughout the study. Patients will be interviewed about the occurrence of AEs at each visit from the first trial related activity after the subject has signed the informed consent. Subjects that experience adverse events or develop a disease during the trial period will be managed until the condition is cured or stationary. If this is not the case at the end of the study, subjects will be referred to a relevant physician, e.g. the general practitioner or a specialist, to be followed up.

Time frame: From enrollment to the end of the 3 year study period.