To the Editor:
Although we read with interest the recent article regarding the accuracy of malignant hyperthermia (MH) diagnoses in hospital discharge records,1 we were concerned by aspects of the study’s methodology and data analysis. Two clinicians out of a panel of five assessed each coded MH diagnosis, and categorization was based on the agreement of two clinicians; in the event of a disagreement, a third clinician categorized the case to create a majority. It is unclear both why this method was used instead of the consensus-driven Delphi approach, given that expert opinion was the accepted standard, and why a κ statistic was not provided to demonstrate the strength of agreement between the two raters. In addition, although the study used the MH Clinical Grading Scale to standardize the diagnosis, no data on the calculated Clinical Grading Scale scores of the patients in the study were provided. These data would have added transparency and validity to the results of this study.
Furthermore, the study accepted any previously reported diagnosis of MH in the patient or family member as susceptibility for MH. The data of the study itself suggest that this is not valid, in that the results cast doubt on any reported family or patient history of MH. The combined number of incorrectly coded MH diagnoses categorized as “Fever unrelated to MH” or “Other [non-MH]” was greater than the number of incidents that the study found correctly coded for MH. Pinyavat et al. stated that they “did not consider personal and/or family history cases as coded in error,” but because only medical records for the index hospitalization of each patient were reviewed, it is impossible to determine whether the patient and/or family histories were actual incidents of MH. A true accepted standard exists to determine MH susceptibility, through caffeine–halothane contracture testing, as referenced in the study. There may be a number of patients who receive the MH International Classification of Diseases code without having an actual personal or family history due to relying on previously reported incidents of MH instead of the results of accepted standard testing. Thus, we feel that the published conclusion that 47% of the International Classification of Diseases–coded diagnoses referred to MH susceptibility is misleading because of the high rate of incidents with miscoded diagnoses and that the actual susceptibility could be less.
The authors declare no competing interests.