Treatment of bone loss in patients with chronic liver disease awaiting liver transplantation

Increased Imminent Fracture Risk in Liver Transplant Recipients Despite Bisphosphonate Therapy

BACKGROUND

Bone loss is significant after orthotopic liver transplant (OLT) and is associated with increased fracture risk and decreased quality of life. In post-transplant fracture prevention, the cornerstone of therapeutic management is bisphosphonates.

METHODS

We conducted a retrospective study in a cohort of 155 OLT recipients who received a bisphosphonate prescription at hospital discharge between 2012 and 2016 to investigate post-OLT fragility fracture incidence and predictive risk factors.

RESULTS

Before OLT, 14 patients presented a T score < -2.5 SD, and 23 patients (14.8%) had a history of fracture. During follow-up, the cumulative incidence of fractures on bisphosphonates (99.4% risedronate/alendronate) was 9.7% at 12 months and 13.1% at 24 months. The median time to first fragility fracture was 10 months (IQR, 3-22 months) and thus within the first 2 years of follow-up. Predictive factors of fragility fractures in multivariate Cox regression analyses included age 60 years or older (hazard ratio [HR], 2.61; 95% CI, 1.14-6.01; P = .02), post-transplant diabetes mellitus (HR, 3.82; 95% CI, 1.55-9.44; P = .004), and cholestatic disease (HR, 5.93; 95% CI, 2.30-15.26; P = .0002). Additionally, the female sex was associated with a strong trend toward increased fracture risk in univariate analysis (HR, 2.27; 95% CI, 1.00-5.15; P = .05), as well as a post-transplant absolute decrease in bone mineral density at the femoral neck and total hip (P = .08).

CONCLUSIONS

This real-world study reports a high incidence of fractures post-OLT despite bisphosphonate therapy. Age 60 years or older, post-transplant diabetes mellitus, cholestatic disease, female sex, and femoral neck and/or total hip bone mineral density loss contribute to increased imminent fracture risk in liver transplant recipients.

Bone Health in Patients With Liver Diseases

Osteoporosis is the most common bone disease in chronic liver disease (CLD) resulting in frequent fractures and leading to significant morbidity in this population. In addition to patients with cirrhosis and chronic cholestasis, patients with CLD from other etiologies may be affected in the absence of cirrhosis. The mechanism of osteoporosis in CLD varies according to etiology, but in cirrhosis and cholestatic liver disease it is driven primarily by decreased bone formation, which differs from the increased bone resorption seen in postmenopausal osteoporosis. Direct toxic effects from iron and alcohol play a role in hemochromatosis and alcoholic liver disease, respectively. Chronic inflammation also has been proposed to mediate bone disease in viral hepatitis and nonalcoholic fatty liver disease. Treatment trials specific to osteoporosis in CLD are small, confined to primary biliary cholangitis and post-transplant patients, and have not consistently demonstrated a benefit in this population. As it stands, prevention of osteoporosis in CLD relies on the mitigation of risk factors such as smoking and alcohol use, treatment of underlying hypogonadism, and encouraging a healthy diet and weight-bearing exercise. The primary medical intervention for the treatment of osteoporosis in CLD remains bisphosphonates though a benefit in terms of fracture reduction has never been shown. This review outlines what is known regarding the pathogenesis of bone disease in CLD and summarizes current and emerging therapies.

Diagnosis and Management of Cirrhosis-Related Osteoporosis

Management of cirrhosis complications has greatly improved, increasing survival and quality of life of the patients. Despite that, some of these complications are still overlooked and scarcely treated, particularly those that are not related to the liver. This is the case of osteoporosis, the only cirrhosis complication that is not solved after liver transplantation, because bone loss often increases after immunosuppressant therapy. In this review, the definitions of bone conditions in cirrhotic patients are analyzed, focusing on the more common ones and on those that have the largest impact on this population. Risk factors, physiopathology, diagnosis, screening strategies, and treatment of osteoporosis in cirrhotic patients are discussed, presenting the more striking data on this issue. Therapies used for particular conditions, such as primary biliary cirrhosis and liver transplantation, are also presented.

Bone health and vitamin D status in alcoholic liver disease

Alcohol consumption is harmful to many organs and tissues, including bones, and it leads to osteoporosis. Hepatic osteodystrophy is abnormal bone metabolism that has been defined in patients with chronic liver disease (CLD), including osteopenia, osteoporosis, and osteomalacia. Decreased bone density in patients with CLD results from decreased bone formation or increased bone resorption. The prevalence of osteopenia in alcoholic liver disease (ALD) patients is between 34 % and 48 %, and the prevalence of osteoporosis is between 11 % and 36 %. Cirrhosis is also a risk factor for osteoporosis. The liver has an important role in vitamin D metabolism. Ninety percent of patients with alcoholic liver cirrhosis have vitamin D inadequacy (<80 nmol/L). The lowest serum vitamin D levels were observed in patients with Child-Pugh class C. Bone densitometry is used for the definitive diagnosis of osteoporosis in ALD. There are no specific controlled clinical studies on the treatment of osteoporosis in patients with ALD. Alcohol cessation and abstinence are principal for the prevention and treatment of osteoporosis in ALD patients, and the progression of osteopenia can be stopped in this way. Calcium and vitamin D supplementation is recommended, and associated nutritional deficiencies should also be corrected. The treatment recommendations of osteoporosis in CLD tend to be extended to ALD. Bisphosphonates have been proven to be effective in increasing bone mineral density (BMD) in chronic cholestatic disease and post-transplant patients, and they can be used in ALD patients. Randomized studies assessing the management of CLD-associated osteoporosis and the development of new drugs for osteoporosis may change the future. Here, we will discuss bone quality, vitamin D status, mechanism of bone effects, and diagnosis and treatment of osteoporosis in ALD.

Patient selection for liver transplantation

Improved outcomes in liver transplant recipients reflect advances in surgical technique, post-operative care, immunosuppression as well as better selection of potential candidates. The pre-transplant evaluation is a multidisciplinary process intended to recognize and treat important comorbid conditions that may impair outcomes during the peri- and post-transplant periods. Important psychosocial issues should also be ascertained and tackled early during the pre-transplant evaluation with an overarching intention to improve the success of liver transplantation.

High prevalence of vitamin A deficiency and vitamin D deficiency in patients evaluated for liver transplantation

Deficiencies in vitamins A, D, and E have been linked to night blindness, bone health, and post-liver transplant reperfusion injury. The aim of this study was to determine the prevalence and predictive factors of fat-soluble vitamin deficiencies in liver transplant candidates. We reviewed the medical records of liver transplant candidates at our center from January 2008 to September 2011. The etiology of cirrhosis, Model for End-Stage Liver Disease score, Child-Pugh class, body mass index (BMI), and vitamin A, vitamin E, and vitamin 25-OH-D levels were recorded. Patients were excluded for incomplete laboratory data, short gut syndrome, celiac disease, pancreatic insufficiency, or prior liver transplantation. Sixty-three patients were included. The most common etiologies of liver disease were alcohol (n = 23), hepatitis C virus (n = 19), and nonalcoholic steatohepatitis (n = 5). Vitamin A and D deficiencies were noted in 69.8% and 81.0%, respectively. Only 3.2% of the patients were vitamin E-deficient. There were no documented cases of night blindness. Twenty-five of the 55 patients with bone density measurements had osteopenia, and 10 had osteoporosis. Four patients had vertebral fractures. There was 1 case of posttransplant reperfusion injury in a patient with vitamin E deficiency. In a multivariate analysis, there were no statistically significant predictors for vitamin D deficiency. The Child-Pugh class [odds ratio (OR) = 6.84, 95% confidence interval (CI) = 1.52-30.86, P = 0.01], elevated total bilirubin level (OR = 44.23, 95% CI = 5.02-389.41, P < 0.001), and elevated BMI (OR = 1.17, 95% CI = 1.00-1.36, P = 0.045) were found to be predictors of vitamin A deficiency. In conclusion, the majority of liver disease patients evaluated for liver transplantation at our center had vitamin A and D deficiencies. The presence or absence of cholestatic liver disease did not predict deficiencies, whereas Child-Pugh class, bilirubin level, and elevated BMI predicted vitamin A deficiency.