Continued Efficacy and Safety of Zoledronic Acid (q 4 Wks vs. q 12 Wks) in the 2nd Year of Treatment in Patients With Bone Metastases From Breast Cancer

An SRE was defined as a pathologic fracture (vertebral and non-vertebral), spinal cord compression, radiation to bone or surgery to bone.

An SRE was defined as a pathologic bone fracture (vertebral and non-vertebral), spinal cord compression, radiation to bone, or surgery to bone. The time to first individual SRE was defined as the date of randomization to the date of first occurrence of any SRE.

Types of SREs analyzed were pathologic fractures (vertebral and non-vertebral), spinal cord compression, radiation to bone and surgery to bone. The time to first indvidual SRE was defined as the date of randomization to the date of the first occurrence of any individual SRE.

Participants completed a BPI short form which is a 9 item self-administered questionnaire used to evaluate the severity of a participant's pain and the impact of this pain on the participant's daily functioning. The participant rates his or her worst, least, average, and current pain intensity, lists current treatments and perceived effectiveness, and rates the degree that pain interferes with general activity, mood, walking ability, normal work, relations with other persons, sleep, and enjoyment of life on a 10 point scale. The BPI composite score, which was calculated as the average of items 3, 4, 5 and 6 (worst pain, least pain, average pain and pain right now), ranged from 0 (best possible outcome, no pain) to 10 (worst possible outcome, pain as bad as you can imagine). A positive change from baseline indicates worsening.

The analgesic score indicates the types of pain medication used. The scores range as follows: 0 = none medication; 1 = minor analgesics (aspirin, NSAID, acetaminophen, propoxyphene, etc.); 2 = Tranquilizers, antidepressants, muscle relaxants, and steroids; 3 = Mild narcotics (oxycodone, meperidine, codeine, etc.); and 4 = Strong narcotics (morphine, hydromorphone, etc.). A positive change from baseline indicates worsening.

Urine samples were collected to obtain n-telopeptide and creatinine values.

Serum samples were collected to obtain bone specific alkaline phosphatase values.

An SMR for a patient was defined as the "number of occurrences" of any (or a particular) SRE allowing for only 1 event in any 3-week interval, divided by the "time at risk" in years. The "number of occurrences" and the "time at risk" were counts of SRE and the time from the randomization date. Counting began from randomization in the way that every counted event was followed by a 20-day period during which no SRE was counted, nor was the time counted as "at risk". For example, if a patient had 1 SRE during the study, the "time at risk" was calculated as the total number of days in the study minus the 20-day follow-up period for that SRE. If a patient had no SRE events, the entire study period was counted as "time at risk". This SMR calculation method had the advantage of avoiding multiple counts of possibly interdependent SREs (e.g. having 1 fracture increases the probability of having a subsequent SRE).