Nineteen studies with 4,559 patients (3,081 took cetuximab) were included. One of the six RCTs (sample size range 117 to 1,298) scored 5 points on the Jadad scale, four scored 3 and one scored 2. The 13 single-armed trials (sample size range eight to 1,123) were not quality assessed.
Incidence of grade 3/4 hypomagnesaemia was 5.6% (95% CI 3.0% to 10.2%, I2=96%; 19 studies). Incidence of all-grade hypomagnesaemia was 36.7% (95% CI 22% to 54.4%, I2=88%; seven studies). The authors reported that heterogeneity remained when sensitivity and subgroup analyses were performed.
In RCTs that compared cetuximab-based therapy with non-cetuximab-based therapy, cetuximab was associated with a significantly greater risk of grade 3/4 hypomagnesaemia (OR 5.3, 95% CI 2.3 to 12.2, I2=0%; six trials) and all-grade hypomagnesaemia (OR 4.75, 95% CI 3.7 to 6.2, I2=26%; four RCTs).