Prevalence and risk factors of low bone mineral density and 25-hydroxyvitamin D status in young healthy epileptic adult patients in a tropical Asian country taking antiepileptic drug

Serum 25-hydroxyvitamin D, serum calcium and vitamin D receptor (VDR) polymorphisms in a selected population with lumbar disc herniation-A case control study

Background

Association of Vitamin D receptor (VDR) polymorphisms with lumbar disc herniation (LDH) have been identified in several ethnic groups globally. Despite abundant sunlight, vitamin D deficiency is reported in many tropical countries. As vitamin D is a key modulator for intestinal calcium absorption, low vitamin D could contribute to low serum calcium leading to abnormalities of skeletal homeostasis. Therefore, present study was aimed to study the association of serum 25-hydroxyvitamin D (25(OH)D), serum calcium and VDR polymorphisms in a selected Sri Lankan population.

Materials & methods

A case control study was conducted in 119 participants (cases = 51: controls = 68). Serum 25(OH)D levels were measured using ELISA. The VDR polymorphisms (Fok I and Taq I) were detected by polymerase chain reaction followed by restriction fragment length polymorphism.

Results

Findings indicated a significantly low (p = 0.000) 25(OH)D levels in cases (18.7±3.7 ng/mL) compared to controls(25.5±9.8 ng/mL) while 25(OH)D in both groups were below the reference range. Mean serum calcium levels in both groups were within normal reference range and was not significantly different among groups. Statistically significant association was not observed between VDR Fok I polymorphisms among cases and controls. Although Fok I polymorphism genotypes were in Hardy-Weinberg equilibrium (HWE), Taq I genotypes in controls violated HWE.

Conclusion

Present study confirms that insufficient serum 25(OH)D levels in cases have major contribution to LDH. VDR Fok I polymorphisms did not have any significant association with LDH in Sri Lankan ethnicity.

Side-Effects of Convulsive Seizures and Anti-Seizure Therapy on Bone in a Rat Model of Epilepsy

The severe sole effects of seizures on the cortical part of bone were reported in our previous study. However, the side effects of anti-epileptic drug therapy on bones has not been differentiated from the effects of the convulsive seizures, yet. This study provides the first report on differentiation of the effects of seizures and carbamazepine (a widely used antiepileptic drug) therapy on bones; 50 mg/kg/day drug was given to genetically induced absence epileptic rats for five weeks. Distinct bone regions including cortical, trabecular, and growth plate in each of tibia, femur, and spine tissues were studied using Fourier transform infrared (FT-IR) imaging and Vickers microhardness test. Blood levels of vitamin D and bone turnover biomarkers were also measured. According to the FT-IR imaging results, both seizure and carbamazepine-treated groups, more dominantly the drug-treated group, had lower mineral content with altered collagen crosslinks and higher crystallinity, implying reduced bone strength. Lower microhardness values also supported lower mechanical strength in bones. The most affected bone tissue and region from seizures and treatment was found as the spine and cortical, respectively. While there was a reduction in vitamin D and calcium levels in both seizure and carbamazepin-treated groups, significantly elevated PTH and bone turnover biomarkers were only seen in the drug-treated group.

Bipolar disorder and the risk of fracture: A nationwide population-based cohort study

BACKGROUND

The co-primary aims are: 1) to compare the risk of fracture between adults with bipolar disorder and those without bipolar disorder; and 2) to assess whether lithium, anticonvulsants and antipsychotics reduce risk of fracture among individuals with bipolar disorder.

METHODS

The analysis herein is a population-based retrospective cohort study, utilizing the National Health Insurance (NHI) medical claims data collected between 1997 and 2013 in Taiwan. We identified 3705 cases with incident diagnoses of bipolar disorder during study period and 37,050 matched controls without bipolar diagnoses. Incident diagnosis of fracture was operationalized as any bone fracture after the diagnosis of bipolar disorder or after the matched index date for controls.

RESULTS

Bipolar patients had significantly higher risk of facture when compared to matched controls (17.6% versus 11.7%, respectively p<0.001). The hazard ratio (HR) was 1.33 (95% confidence interval [CI]＝1.23-1.48, p<0.001) after adjusting for covariates. Persons with bipolar disorder and a prior history of psychiatric hospitalization were had higher risk for bone fracture than those without prior history of psychiatric hospitalization when compared to match controls. Higher cumulative dose of antipsychotics or mood stabilizers did not increase the risk of fracture.

LIMITATIONS

The diagnoses of bipolar disorder were not confirmed with structured clinical interview. Drug adherence, exact exposure dosage, smoking, lifestyle, nutrition and exercise habits were unable to be assessed in our dataset.

CONCLUSIONS

Bipolar disorder is associated with increased risk of fracture, and higher cumulative dose of mood stabilizers and antipsychotics did not further increase the risk of fracture.

Association between serum levels of bioavailable vitamin D and negative symptoms in first-episode psychosis

Total vitamin D levels had been commonly reported to be lowered in patients with chronic psychotic illnesses in countries from the higher latitudes. However, studies on patients with first episode psychosis (FEP) are limited. In this study we investigated serum concentrations of total and bioavailable vitamin D levels in FEP patients compared to healthy controls and the association between symptom severity and vitamin D components. A total of 31 FEP patients and 31 healthy controls were recruited from Institute of Mental Health, Singapore. FEP patients were identified using Structured Clinical Interview for DSM-IV Axis I disorders (SCID-1) and severity symptoms were assessed using the positive and negative syndrome scale (PANSS). Sera from participants were analyzed for total vitamin D, vitamin D-binding protein (DBP) and bioavailable vitamin D. Linear regressions were performed to examine the associations between serum total and bioavailable vitamin D and the PANSS subscales. Current study noted a significantly lower bioavailable vitamin D was in the FEP group and an association between bioavailable vitamin D and negative symptoms in FEP patients in a population with a consistent supply of sun exposure throughout the year.

Enzyme-inducing antiepileptic drugs and fractures in people with epilepsy: A systematic review

OBJECTIVE

People with epilepsy (PWE) have an increased fracture risk, independent of seizures. Antiepileptic drugs are thought to increase this risk, particularly those that induce the hepatic cytochrome P450 enzyme system. We aimed to determine whether PWE treated with enzyme-inducing antiepileptic drugs (EIAEDs) have decreased bone mineral density (BMD), or increased fracture incidence, versus those treated with non-EIAEDs.

METHODS

We searched MedLine, EMBase, CENTRAL, and CINAHL prior to November 2014 for all studies comparing fracture risk, or BMD change, in PWE treated for ≥ 1 year with EIAEDs versus non-EIAEDs.

RESULTS

Thirteen observational studies met eligibility criteria. These studies, representing 68,973 adult PWE, were significantly heterogeneous, making meta-analysis impossible. Study results were split, with 5 studies showing decreased BMD in EIAED users, 5 studies showing no effect of EIAED on BMD, 2 studies showing increased fracture incidence in EIAED users, and 1 study showing no difference in fracture risk. The largest study (n = 63,259), which was also the most methodologically rigorous, showed an increased hazard ratio of 9-22% for any fracture, and 49-53% for hip fracture, in EIAED users.

SIGNIFICANCE

The literature is divided regarding the bone effects of EIAEDs; however, current best evidence supports an increased fracture risk in PWE treated with an EIAED compared to those treated with non-EIAEDs. A single article dominated our review, and other large methodologically rigorous studies are needed to confirm or refute its results. Further small studies, with limited power to control for multiple potentially confounding variables, are not likely to help.

Survey of risk factors for osteoporosis and osteoprotective behaviors among patients with epilepsy

The prevalence of risk factors for osteoporosis in persons with epilepsy, patients' awareness of their risk, and their engagement in osteoprotective behaviors were assessed in this study. Two hundred and sixty patients with epilepsy (F=51.5%, average age=42) completed a survey tool. Of 106 patients with a dual energy X-ray absorptiometry (DXA) result, 52% had low bone mineral density, and 11% had osteoporosis. The results suggest that the majority of patients with epilepsy do not engage in bone-protective behaviors. Those who have undergone a DXA scan may be more likely to take calcium and vitamin D supplementation compared with those who did not undergo a DXA scan, but they do not engage in other osteoprotective behaviors. Many patients did not accurately report their DXA results, indicating that better patient education is warranted.

Antiepileptic drugs and high prevalence of low bone mineral density in a group of inpatients with chronic epilepsy

PURPOSE

Long-term antiepileptic drug use is associated with low bone mineral density (BMD), fractures and abnormalities in bone metabolism. We aimed at determining the prevalence of bone mineral disorders in patients with refractory epilepsy treated with antiepileptic drugs.

METHODS

A cross-sectional survey was conducted in adult patients (n = 205) from a residential unit of a tertiary epilepsy centre. Screening for bone mineral disorders was performed with dual-energy X-ray absorptiometry (DXA) scan of spine and hip (including bone mineral density and vertebral fracture assessment) and laboratory measurements. Patient information regarding demography, epilepsy characteristics and medication use was recorded. Based on DXA T-scores, prevalence of bone mineral disorders (osteopenia and osteoporosis) was calculated. Correlations between DXA T-scores and epilepsy parameters were explored.

RESULTS

Of the 205 patients, there were 10 dropouts. 80% (n = 156/195) of the patients had low BMD: 48.2% had osteopenia and 31.8% had osteoporosis. Of those having low BMD, 51.9% (n = 81/195) was between 18 and 50 years. The T-score of the femoral neck correlated significantly with total duration of epilepsy, cumulative drug load and history of fractures. Linear regression analysis showed that of the epilepsy-related parameters, only cumulative drug load significantly predicted low femoral neck T-score (P = 0.001).

CONCLUSION

In this high-risk population, we obtained a very high prevalence of 80% of low BMD. Both men and women were affected as well as patients <50 years of age. This study illustrates the magnitude of the problem of bone mineral disorders in chronic epilepsy.

The association between CYP 2C9 polymorphism and bone health

PURPOSE

There is a strong scientific rationale to support the view that cytochrome P450 (CYP P450) enzyme-inducing AEDs induce bone loss in patients with epilepsy. However, no study has investigated the association between CYP 2C9 polymorphism and bone mineral density (BMD), 25-hydroxyvitamin D or parathyroid hormone levels in patients with epilepsy. This study sought to determine the association between BMD and CYP 2C9 polymorphism.

METHODS

Ninety-three patients taking phenytoin as monotherapy were examined for CYP 2C9 polymorphism, vitamin D level and parathyroid hormone level and underwent basic chemistry testing. The bone mineral density of the lumbar spine and left femur were measured using dual-energy X-ray absorptiometry.

RESULTS

The results indicated that about 18.3% of the patients with epilepsy were positive for CYP2C9*3. Furthermore, bone mineral density was associated with CYP 2C9 polymorphism epileptic patients. Specifically, patients with 2C9 polymorphism had higher T-scores and Z-scores of the femoral neck (p=0.02 and 0.04, respectively), but not of the lumbar spine (p=0.27 and 0.06, respectively). There was also a trend of having higher serum PTH levels and statistically significantly lower 25-hydroxyvitamin D levels in patients with wild type than in those compared with CYP 2C9 polymorphism (p=0.05 and 0.03, respectively). Additionally, the patients with CYP 2C9 polymorphism had higher plasma levels of phenytoin, particularly when compared with those with wild type (p=0.01). However, there was no association between serum levels of phenytoin and low BMD at femoral neck or lumbar spine.

CONCLUSION

CYP 2C9 polymorphism is associated with higher BMD, independent of plasma levels of phenytoin.

Bone health in adults with epilepsy

Patients with epilepsy have a 2-6 times greater risk of bone fractures compared with the general population. There are several potential explanations. Some fractures are caused by seizure-related injuries, or they may be associated with the osteopenic effect of reduced physical activity in patients with epilepsy. Antiepileptic drugs (AEDs), especially those that affect the liver enzymes, e.g., phenytoin, carbamazepine, phenobarbital, as well as valproate, are also associated with increased fracture rate and low bone mineral density. Many patients with epilepsy and general practitioners seem unaware of this problem. Measurements of bone density should be taken regularly in patients at risk of developing osteoporosis. Non-pharmaceutical initiatives, such as partaking in regular physical activity and eating a well-balanced diet, should be recommended. The risk of developing osteoporosis should be taken into consideration in the selection of an AED for treating a newly diagnosed patient with epilepsy.