Interventions for hereditary haemochromatosis: an attempted network meta-analysis

Hereditary haemochromatosis is a genetic disorder related to proteins involved in iron transport, resulting in iron load and deposition of iron in various tissues of the body. This iron overload leads to complications including liver cirrhosis (and related complications such as liver failure and hepatocellular carcinoma), cardiac failure, cardiac arrhythmias, impotence, diabetes, arthritis, and skin pigmentation. Phlebotomy (venesection or 'blood letting') is the currently recommended treatment for hereditary haemochromatosis. The optimal treatment of hereditary haemochromatosis remains controversial.

To assess the comparative benefits and harms of different interventions in the treatment of hereditary haemochromatosis through a network meta-analysis and to generate rankings of the available treatments according to their safety and efficacy. However, we found only one comparison. Therefore, we did not perform the network meta-analysis and we assessed the comparative benefits and harms of different interventions using standard Cochrane methodology.

We searched the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE, Embase, Science Citation Index Expanded, World Health Organization International Clinical Trials Registry Platform, and randomised clinical trials registers to March 2016 to identify randomised clinical trials on treatments for hereditary haemochromatosis.

We included only randomised clinical trials (irrespective of language, blinding, or publication status) in participants with hereditary haemochromatosis. We excluded trials which included participants who had previously undergone liver transplantation. We considered any of the various interventions compared with each other or with inactive treatment.

We used standard methodological procedures expected by Cochrane. We calculated the odds ratio (OR) and rate ratio with 95% confidence intervals (CI) using both fixed-effect and random-effects models with RevMan 5 based on available-participant analysis. We assessed risk of bias according to Cochrane, controlled risk of random errors with Trial Sequential Analysis, and assessed the quality of the evidence using GRADE.

Three trials with 146 participants met the inclusion criteria of this review. Two parallel group trials with 100 participants provided information on one or more outcomes. The remaining trial was a cross-over trial, with no usable data for analysis. All the trials were at high risk of bias. Overall, all the evidence was of very low quality. All three trials compared erythrocytapheresis (removal of red cells only, instead of whole blood) versus phlebotomy. Two of the trials shared the same first author. The mean or median age in the three trials ranged from 42 to 55 years. None of the trials reported whether the included participants were symptomatic or asymptomatic or a mixture of both. Two trials were conducted in people who were haemochromatosis treatment-naive. The trial that provided most data for this review excluded people with malignancy, heart failure, and serious cardiac arrhythmias. We found no trials assessing iron-chelating agents.Only one of the trials with 38 participants reported no short-term mortality and no serious adverse events at the end of the short-term follow-up (eight months). Two trials reported the proportion of people with adverse events: 10/49 (20.4%) in the erythrocytapheresis group versus 11/51 (21.6%) in the phlebotomy group. One of these two trials provided data on adverse event rates (42.1 events per 100 participants with erythrocytapheresis versus 52.6 events per 100 participants with phlebotomy). There was no evidence of differences in the proportion of people with adverse events and the number of adverse events (serious and non-serious) between the groups (proportion of people with adverse events: OR 0.93, 95% CI 0.36 to 2.43; participants = 100; trials = 2; number of adverse events: rate ratio 0.80, 95% CI 0.32 to 2.03; participants = 38; trial = 1). There was no difference between the groups regarding short-term health-related quality of life (mean difference (MD) 1.00, 95% CI -10.80 to 12.80; participants = 38; trials = 1). This outcome was measured using EQ-VAS (range: 0 to 100 where a higher score indicates better health-related quality of life). None of the trials reported mortality beyond one year, health-related quality of life beyond one year, liver transplantation, decompensated liver disease, cirrhosis, hepatocellular carcinoma, diabetes, or cardiovascular complications during the long-term follow-up.The two trials that provided data for this review were funded by parties with no vested interest in the results; the source of funding of the third trial was not reported.

There is currently insufficient evidence to determine whether erythrocytapheresis is beneficial or harmful compared with phlebotomy. Phlebotomy has less equipment requirements and remains the treatment of choice in people with hereditary haemochromatosis who require blood letting in some form. However, it should be noted that there is no evidence from randomised clinical trials that blood letting in any form is beneficial in people with hereditary haemochromatosis. Having said this, a trial including no treatment is unlikely to be conducted. Future trials should compare different frequencies of phlebotomy and erythrocytapheresis versus phlebotomy with and without different iron-chelating agents compared with each other, and with placebo. Such trials should include long-term follow-up of participants (e.g. using national record linkage databases) to determine whether treatments are beneficial or harmful in terms of clinical outcomes such as deaths, health-related quality of life, liver damage and its consequences, heart damage and its consequences, and other outcomes that are of importance to people with hereditary haemochromatosis.