In reply

Black cohosh and suspected hepatotoxicity: inconsistencies, confounding variables, and prospective use of a diagnostic causality algorithm. A critical review

OBJECTIVE

The data of 69 cases of initially suspected black cohosh (BC)-induced liver disease were reviewed and analyzed to clarify whether BC hepatotoxicity really exists as a disease entity in these cases comparable to toxic liver disease being caused by various drugs and dietary supplements.

METHODS

The cases comprised 11 published case reports and 58 spontaneous reports to national regulatory agencies. The analysis includes assessment of causality for BC, data quality of the presented cases, and their inconsistencies and confounding variables.

RESULTS

The assessed data raise serious doubts on the initial claims of causality for BC in these cases and provide clear evidence of their poor quality, especially when spontaneous reports are considered. There are major inconsistencies for the same patient regarding reported data. Moreover, the analysis of all cases disclosed confounding variables. These include poor case data quality, uncertainty of BC product, quality, and identification, undisclosed indication, insufficient adverse event definition, lack of temporal association and dechallenge, missing or inadequate evaluation of alcohol use, comedication, comorbidity, reexposure test, and alternative diagnoses.

CONCLUSIONS

The presented data do not support the concept of hepatotoxicity in a primarily suspected causal relationship to the use of BC and failure to provide a signal of safety concern, but further efforts have to be undertaken to dismiss or to substantiate the existence of BC hepatotoxicity as a special disease entity. The future strategy should be focused on prospective causality evaluations in patients diagnosed with suspected BC hepatotoxicity, using a structured, quantitative, and hepatotoxicity-specific causality assessment method.

Suspected black cohosh hepatotoxicity--challenges and pitfalls of causality assessment

OBJECTIVES

Black cohosh (BC) is a herbal drug or herbal dietary supplement used for treatment of menopausal symptoms. Recently, however, reports have appeared about the occurrence of rare toxic liver disease in an assumed relationship with the use of BC.

METHODS

We have analyzed and reviewed the data of all 69 reported cases with suspected BC hepatotoxicity. Causality for BC was assessed utilizing the scale of the original structured quantitative Council for International Organizations of Medical Sciences (CIOMS), or the main-test as its updated form.

RESULTS

With the hepatotoxicity specific causality assessment methods, there was an excluded, unlikely, unrelated or unassessable causality for BC in 68 of 69 cases with liver disease. One patient had a possible causality for BC and a symptomatic cholelithiasis with confounding variables of fatty liver of unknown etiology; unknown BC brand including possible herbal mixture; unknown daily BC dosage; and an unassessable duration of BC usage. In general, the cases of the 69 patients were poorly documented. Confounding variables were: failure to identify the BC product; use of herbal mixtures with multiple ingredients in addition to BC; co-medication with synthetic drugs and dietary supplements including herbal ones; missing temporal association between BC use and development of liver disease; not specified modalities of BC treatment; failure of dechallenge after BC discontinuation; pre-existing liver diseases; insufficiently excluded other liver diseases; presence of alternative liver diseases.

CONCLUSIONS

The analysis of 69 cases shows little, if any, supportive evidence for a significant hepatotoxic risk of BC.