The safety and cost-effectiveness of low osmolar contrast media. Can economic analysis determine the real worth of a new technology?

Objectives: To estimate the reduction in mortality associated with a reduced adverse reaction rate following the substitution of older high osmolar radiocontrast media (HOCM) by the newer and more expensive low osmolar contrast media (LOCM), and to assess the cost-effectiveness of switching from HOCM to LOCM in patients with and without underlying risk factors for adverse reactions from radiocontrast agents. Data sources: Data from large prospective studies of adverse reactions to HOCM and LOCM were used to estimate the expected number of deaths and severe non-fatal reactions in a hypothetical population receiving one million intravenous radiocontrast injections with HOCM, and the expected reduction in the frequency of these outcomes after substitution by LOCM in high-risk and low-risk groups respectively. Life-years lost with each radiocontrast-related death were estimated from an audit of fatal adverse reaction reports submitted to the Adverse Drug Reactions Advisory Committee. The direct costs considered in the study were the increased costs of LOCM and the hospital costs of treating radiocontrast reactions which were estimated from an audit of cases admitted to public hospitals in Newcastle. Study selection: The literature search included Medline (1968-1989) and bibliographies of original and review articles. We included only studies which were prospective, monitored patients in a formal way, described a mechanism for the recording of adverse events and were of sufficient size to have been capable of detecting severe reactions to radiocontrast agents. Data extraction: Data were extracted independently by two investigators, unblinded, with disagreements resolved by consensus. Data synthesis: Mortality data from individual reports were pooled and exact confidence intervals were calculated on the assumption of a Poisson distribution. In the case of comparative studies the relative risks of severe reactions in low-risk versus high-risk patients and with LOCM compared with HOCM were treated for homogeneity, and pooled odds ratios and 95% confidence intervals (CI) were calculated by combining the logarithms of the odds ratios weighted by their variances. Results: The mortality after intravenous administration of HOCM was estimated from all studies to be 23.3 (95% CI, 2.4-38.1) per million injections. However, the mortality was 11.7 per million (95% CI, 2.4-34.1) in studies published since 1986. The mortality after the use of LOCM was estimated as 3.9 per million (95% CI, 0.1 -21.7). The cost-effectiveness ratios for substitution of HOCM by LOCM were $898540 per life saved, $47186 per life-year gained and $13029 per severe reaction averted in high-risk patients, and $2.8 million per life saved, $147235 per life-year gained and $57559 per severe reaction averted in low-risk patients. Conclusion: The cost-effectiveness of administering LOCM to low-risk patients compares poorly with that of other expensive medical interventions and scarce resources would be better directed to other uses.