Subgroup and cost-benefit analysis of the Finnish multicentre trial of clodronate in multiple myeloma

Osteolytic lesions and pathological fractures are the major problems in the clinical management of multiple myeloma. We previously reported the main results of a randomized, controlled multicentre trial in 350 Finnish patients with multiple myeloma. All patients received standard melphalan-prednisolone treatment and were randomized to receive either clodronate 2.4 g daily or a placebo for 24 months. The proportion of patients with progression of osteolytic bone lesions was twice as high in the placebo group as in the clodronate group (24.0%v 12.0%, P= 0.026). The purpose of the present study was to investigate factors associated with the progression of osteolytic lesions and to identify subgroups of patients who would benefit most from clodronate treatment. In univariate logistic regression analysis, including treatment (placebo, clodronate), sex, age, pain index, serum calcium and creatinine, myeloma stage, number of osteolytic lesions at baseline, and number of vertebral fractures at baseline as independent variables and the progression of osteolytic lesions as a dependent variable, only the treatment with a placebo was associated with the progression of osteolytic bone lesions. Separate analyses with respect to the progression of osteolytic bone lesions were carried out in the following subgroups: male v female, ± 64 v > 64 years, stage I v stage II-III myeloma, no osteolytic lesions at baseline versus osteolytic lesions at baseline, no vertebral fractures at baseline versus vertebral fractures at baseline, and a 50% treatment response to cytotoxic drugs versus no treatment response to cytotoxic drugs. The treatment with clodronate delayed the progression of osteolytic lesions similarly in these subgroups, with the exception of a subgroup of patients who did not have a 50% treatment response to cytotoxic drugs. The treatment with clodronate did not significantly increase treatment costs. We conclude that the treatment effect of clodronate seems to be independent of sex and age of the patients, the stage of myeloma, and the severity of bone lesions at diagnosis, but not of treatment response to cytotoxic drugs.