Vertebral fractures are the most common osteoporotic fractures, and new vertebral fractures occur more frequently in women with preexisting fractures. Previous studies have demonstrated that treating women who have existing vertebral fractures with the bisphosphonate alendronate sodium significantly reduced the rate of new vertebral fractures. Women with new vertebral fractures have an increased risk of back pain and functional limitation. Nevitt and associates evaluated the effect of alendronate therapy on days affected by back pain in postmenopausal women with existing vertebral fractures.

A total of 2,027 postmenopausal women aged 55 to 81 years with low femoral neck bone density and at least one preexisting vertebral fracture were enrolled in the Fracture Intervention Trial at 11 clinical centers. The women were randomized to receive alendronate sodium (5 mg per day for two years and 10 mg per day for the third year) or placebo. Treatment and follow-up continued for three years. Patients were questioned about back pain and limitation at regular clinic visits every three months. These questions were adapted from a previous national health survey assessing days of limited activity caused by health conditions. Physical disability was assessed at baseline and again at the end of the study. Lateral radiographs were obtained at baseline and 36 months after randomization. New vertebral fractures were defined as a decrease of 20 percent and at least 4 mm in any vertebral height.

Back pain during follow-up was common regardless of whether or not women experienced a new vertebral fracture by the end of the study. Among women with new fractures, the majority reported at least seven days of moderate to severe back pain and at least seven days of limited activity because of the pain. More than 50 percent of women with a new fracture had to undergo seven or more days of bed rest. The limited activity and bed rest caused by back pain was significantly increased if a new fracture occurred, and the disability was similar in both study groups.

Women in the alendronate-treated group had 63 percent fewer bed-rest days because of back pain compared with patients receiving placebo. At each point during the follow-up period, the percentage of patients reporting at least one day of bed rest was consistently lower in the active drug group. The mean number of days of limited activity because of back pain was 16 percent lower in the alendronate group than in the placebo group. The mean number of days with any back pain was similar in both groups. Of the 1,843 women who were measured by back disability scores, 8.5 percent had new or worsening disability at the close of the study. There were no significant differences between treatment groups for change in disability score from entry to end point.

Results of this study demonstrate that the number of days affected by back pain increased dramatically after the occurrence of a new vertebral fracture. The authors conclude that treating these patients with alendronate reduced the number of days affected by back pain. The reduction was greater for the more severe and less frequent events and days in bed because of the back pain than for the less severe pain and limited activity days and days with back pain. The authors suggest the effect of alendronate on days affected by back pain is explained in part by the 50 percent reduction in the occurrence of new vertebral fractures in women treated with alendronate. Treatment of postmenopausal women who have at least one vertebral fracture with alendronate sodium in dosages of 5 to 10 mg per day during a three-year period was effective in preventing new fractures and significantly reduced the functional disability caused by back pain.