Prevalence of Rhabdomyolysis in Sympathomimetic Toxicity: a Comparison of Stimulants.

Synthetic cathinones have emerged as popular drugs of abuse and produce sympathomimetic toxicity. It is unknown if rhabdomyolysis occurs more frequently following the use of synthetic cathinones compared to other stimulants. This retrospective study sought to determine the prevalence of rhabdomyolysis in patients with sympathomimetic toxicity and compare rates among patients using specific agents. Patients greater than 14 years of age with sympathomimetic toxicity and detection of a stimulant agent in urine via gas chromatography-mass spectroscopy (GC-MS) were included. Patients were excluded if clinical sympathomimetic toxicity was not present, a serum creatine kinase (CK) was not measured, or urine GC-MS was not performed. Rhabdomyolysis and severe rhabdomyolysis were defined as CK > 1000 and 10,000 IU/L, respectively. Prevalence of rhabdomyolysis and severe rhabdomyolysis were reported. Logistic regression was performed to determine the relative effect in single-agent exposures of a synthetic cathinone compared to other sympathomimetics on rhabdomyolysis. A secondary outcome, a composite endpoint defined as need for mechanical ventilation, renal replacement therapy, development of compartment syndrome, or death, was also analyzed. One hundred two subjects met inclusion criteria; median age (IQR) was 32 (25-42) years with a range of 14-65 years; 74 % were male. Rhabdomyolysis occurred in 42 % (43/102) of subjects. Patients whose sympathomimetic toxicity could be ascribed to a single agent were considered for further statistical analysis and placed into four groups: methamphetamine (n = 55), synthetic cathinone (n = 19), cocaine (n = 9), and other sympathomimetic (n = 6). In 89 subjects with single stimulant exposure, the prevalence of rhabdomyolysis was as follows: synthetic cathinone, 12/19 (63 %); methamphetamine, 22/55 (40 %); cocaine, 3/9 (33 %); and other single agent, 0/6 (0 %). The occurrence of severe rhabdomyolysis (CK > 10,000 IU/L) for each of the four groups was synthetic cathinone with 5/19 (26 %), methamphetamine with 2/55 (3.6 %), cocaine with 1/9 (11 %), and other with 0/6 (0 %). Median maximal CK (range) by groups was as follows: synthetic cathinone, 2638 (62-350,000+) IU/L; methamphetamine, 665 (61-50,233) IU/L; cocaine, 276 (87-25,614) IU/L; and other, 142 (51-816) IU/L. A statistically significant difference (p = 0.004) was found when comparing maximal CK among the four groups. Exposure to a synthetic cathinone compared with other sympathomimetics was associated with increased risk of developing rhabdomyolysis and severe rhabdomyolysis with odds ratios of 3.09 and 7.98, respectively. In this cohort of patients with sympathomimetic toxicity, 42 % developed rhabdomyolysis. Synthetic cathinones were associated with an increased risk of rhabdomyolysis and severe rhabdomyolysis compared with other stimulants.