Performance of administrative case definitions for comorbidity in multiple sclerosis in Manitoba and Nova Scotia

Introduction

As the population ages and the prevalence of comorbid conditions increases, the need for feasible, validated methods of comorbidity surveillance in chronic diseases such as multiple sclerosis (MS) increases.

Methods

Using kappa (k) statistics, we evaluated the performance of administrative case definitions for comorbidities commonly observed in MS by comparing agreement between Manitoba (MB) administrative data and self-report (n = 606) and Nova Scotia (NS) administrative data and self-report (n = 1923).

Results

Agreement between the administrative definitions and self-report was substantial for hypertension (k = 0.69 [NS], 0.76 [MB]) and diabetes (k = 0.70 [NS], 0.66 [MB]); moderate for hyperlipidemia (k = 0.53 [NS], 0.51 [MB]) and heart disease (k = 0.42 [NS], 0.51 [MB]) and fair for anxiety (k = 0.27 [NS], 0.26 [MB]). In NS, agreement was substantial for inflammatory bowel disease (k = 0.71) and moderate for epilepsy (k = 0.48).

Conclusion

Administrative definitions for commonly observed comorbidities in MS performed well in 2 distinct jurisdictions. This suggests that they could be used more broadly across Canada and in national studies.

Performance of administrative case definitions for comorbidity in multiple sclerosis in Manitoba and Nova Scotia

INTRODUCTION

As the population ages and the prevalence of comorbid conditions increases, the need for feasible, validated methods of comorbidity surveillance in chronic diseases such as multiple sclerosis (MS) increases.

METHODS

Using kappa (k) statistics, we evaluated the performance of administrative case definitions for comorbidities commonly observed in MS by comparing agreement between Manitoba (MB) administrative data and self-report (n = 606) and Nova Scotia (NS) administrative data and self-report (n = 1923).

RESULTS

Agreement between the administrative definitions and self-report was substantial for hypertension (k = 0.69 [NS], 0.76 [MB]) and diabetes (k = 0.70 [NS], 0.66 [MB]); moderate for hyperlipidemia (k = 0.53 [NS], 0.51 [MB]) and heart disease (k = 0.42 [NS], 0.51 [MB]) and fair for anxiety (k = 0.27 [NS], 0.26 [MB]). In NS, agreement was substantial for inflammatory bowel disease (k = 0.71) and moderate for epilepsy (k = 0.48).

CONCLUSION

Administrative definitions for commonly observed comorbidities in MS performed well in 2 distinct jurisdictions. This suggests that they could be used more broadly across Canada and in national studies.

β1-Adrenergic receptor polymorphisms influence the response to metoprolol monotherapy in patients with essential hypertension

OBJECTIVES

The human beta(1)-adrenergic receptor, an important therapeutic target in cardiovascular diseases, has 2 common functional polymorphisms (Ser49Gly and Gly389Arg). Our study aimed to confirm that beta(1)-adrenergic receptor polymorphisms affect the blood pressure response to metoprolol monotherapy in the Chinese population with hypertension.

METHODS

beta(1)-Adrenergic receptor genotype was determined by polymerase chain reaction-restriction fragment length polymorphism assay for 223 patients with essential hypertension. Sixty-one patients with certain beta(1)-adrenergic receptor diplotypes, 18 for 49Ser389Arg/49Ser389Arg, 15 for 49Ser389Arg/49Gly389Arg, 19 for 49Ser389Gly/49Gly389Arg, and 9 for 49Ser389Gly/49Ser389Gly, were selected from those 61 for measurement of the antihypertensive effect of metoprolol. Patients were given 25 mg metoprolol every 12 hours for 4 weeks. Heart rate and blood pressure were measured weekly for the duration of metoprolol therapy.

RESULTS

The descent of systolic blood pressure after metoprolol administration was significantly different among genotype groups (10.4% +/- 4.0%, 2.8% +/- 4.7%, and 1.1% +/- 1.5% for Arg389Arg, Gly389Arg, and Gly389Gly patients, respectively; P < .001). We also found a similar difference in changes of diastolic blood pressure (6.1% +/- 4.3%, 2.2% +/- 4.2%, and 0.9% +/- 4.0%, respectively; P < .001) and mean arterial pressure (8.1% +/- 3.5%, 2.5% +/- 3.0%, and 1.0% +/- 2.5%, respectively; P > .001) for Arg389Arg, Gly389Arg, and Gly389Gly patients. Ser49Gly variance exhibited a smaller contribution to the antihypertensive effect of metoprolol. Systolic blood pressure decreased significantly in Ser49 homozygous patients compared with Ser49Gly patients (8.4% +/- 3.2% versus 5.3% +/- 5.2%, P = .047). There was a highly significant relationship between diplotype and blood pressure during treatment. Systolic blood pressure significantly decreased in 49Ser389Arg/49Ser389Arg (12.0% +/- 3.8%, P < .001) and 49Ser389Arg/49Gly389Arg (8.4% +/- 5.5%, P < .001) patients, with the decrease in the former being more pronounced (P = .023). We also found a significant decrease in diastolic blood pressure (6.5% +/- 4.7% versus 5.7% +/- 3.2%, respectively; both P < .001) and mean arterial pressure (8.8% +/- 3.2% versus 6.9% +/- 3.7%, respectively; both P < .001) in 49Ser389Arg/49Ser389Arg and 49Ser389Arg/49Gly389Arg patients. However, blood pressure did not change significantly in 49Ser389Gly/49Gly389Arg and 49Ser389Gly/49Ser389Gly patients (all P > .05).

CONCLUSIONS

beta(1)-Adrenergic receptor polymorphism was associated with different blood pressure responses to metoprolol therapy in patients with essential hypertension. 49Ser389Arg/49Ser389Arg and 49Ser389Arg/49Gly389Arg patients were good responders to metoprolol therapy; 49Ser389Arg/49Ser389Arg patients had a larger systolic blood pressure reduction than 49Ser389Arg/49Gly389Arg patients did. 49Ser389Gly/49Gly389Arg and 49Ser389Gly/49Ser389Gly patients were nonresponders to metoprolol antihypertensive therapy.

Effect of SLCO1B1 genetic polymorphism on the pharmacokinetics of nateglinide

AIMS

Nateglinide is a meglitinide analogue with antidiabetic action. A recent study showed that SLCO1B1 (which codes the OATP1B1 gene, also known as OATP-C, OATP2) is a major determinant which markedly affects the pharmacokinetics of repaglinide. Our objective was to assess the association between single nucleotide polymorphisms (SNPs) of SLCO1B1 and the pharmacokinetics of nateglinide.

METHODS

Seventeen healthy volunteers with different SLCO1B1 genotypes (11 with 521TT, four with 521TC and two with 521CC) were enrolled in this study. Each was given a single oral dose of 90 mg nateglinide. Plasma concentrations of nateglinide were measured up to 8 h by HPLC.

RESULTS

The C(max) and AUC(0,infinity) of nateglinide were 83% (P = 0.002) and 82% (P = 0.001) higher in the SLCO1B1521TC subjects (n = 4), and 76% (P = 0.016) and 108% (P = 0.001) higher in the SLCO1B1521CC subjects (n = 2) than in the SLCO1B1521TT subjects (n = 11), respectively. The t(1/2) of nateglinide in SLCO1B1521CC subjects was 78% longer than that in 521TT subjects (P = 0.036). The difference in t(max) values among the three genotypic groups was not statistically significant.

CONCLUSIONS

Our results suggest that OATP1B1-mediated hepatic uptake of nateglinide may be the prior step for its metabolism and elimination. SLCO1B1521T > C SNP might play an important role in the pharmacokinetics of nateglinide.

Role of BCRP 421C>A polymorphism on rosuvastatin pharmacokinetics in healthy Chinese males

BACKGROUND

Rosuvastatin, a novel potent HMG-CoA reductase inhibitor, is excreted into bile mediated by breast cancer resistance protein (BCRP). Our objective was to determine the association between the most frequent single nucleotide polymorphisms (SNPs) of the BCRP (421C>A) and the pharmacokinetics of rosuvastatin.

METHOD

Pre-screening of SLCO1B1 521TC and CYP2C9*1/*3 were performed before this pharmacokinetic study. Fourteen healthy volunteers who are SLCO1B1 521TT and CYP2C9*1/*1 wild-type homozygotes were selected to participate in this study. Seven were 421CC wild-type of BCRP, the others were carriers with at least one 421C>A mutant allele (five subjects had a genotype of 421CA and two were homozygotes of 421AA). Each was given a single oral dose of 20 mg rosuvastatin. The plasma concentrations of rosuvastatin were measured for up to 72 h by LC-MS.

RESULTS

The pharmacokinetic parameters of rosuvastatin showed a significantly difference between the two genotyped groups. The AUC(0-72) and AUC(0-infinity) of rosuvastatin were lower in the 421CC group than in the 421CA+421AA group (33.8+/-11.4 vs. 59.6+/-22.2 ng.h/ml, P=0.018; 34.9+/-11.9 vs. 62.2+/-23.5 ng.h/ml, P=0.018), respectively. The C(max) value was higher in the 421CA+421AA group than that in the 421CC group (9.9+/-5.4 vs. 5.1+/-2.4 ng/ml, P=0.048). The CL/F value was lower in the 421CA+421AA group than that in the 421CC group (384.7+/-161.2 vs. 674.0+/-297.6 l/h, P=0.043). The T(1/2) and T(max) values showed no difference between these groups.

CONCLUSIONS

The BCRP 421C>A polymorphism may play an important role in the pharmacokinetics of rosuvastatin in healthy Chinese males after the exclusion of impact of SLCO1B1 and CYP2C9 genetic polymorphism.

Gender specific association of CYP2C9*3 with hyperlipidaemia in Chinese

AIMS

To investigate the association of CYP2C9*3 and *6 with hyperlipidaemia in Chinese.

METHODS

Four hundred and seventy-six Chinese participated in the study, including 211 uncomplicated hyperlipidaemic patients and 265 healthy controls. PCR-RFLP was used to identify CYP2C9*3 and *6.

RESULTS

CYP2C9*6 was not detected in this study. The allelic frequency of CYP2C9*3 was 0.039 (95% CI 0.022, 0.056). A nonsignificant difference existed in CYP2C9*3 frequencies between males and females (P = 0.605, OR = 1.194, 95% CI 0.610, 2.336), patients and controls (P = 0.063, OR = 0.506, 95% CI 0.244, 1.049) in the total population. However, in the female group, CYP2C9*3 frequency in patients with hyperlipidaemia was significantly lower than that in controls (P < 0.0001, OR = 0.062, 95% CI 0.008, 0.476).

CONCLUSIONS

The association of CYP2C9*3 with hyperlipidaemia was specific for females in this Chinese population.

Ile118Val genetic polymorphism of CYP3A4 and its effects on lipid-lowering efficacy of simvastatin in Chinese hyperlipidemic patients

OBJECTIVES

To determine the frequencies of CYP3A4 alleles (CYP3A4*4,*5 and *6) in Chinese hyperlipidemic patients and to observe the impact of CYP3A4*4 (Ile118Val) genetic polymorphism on the lipid-lowering effects of simvastatin and on the activity of CYP3A4.

METHODS

From hospitalized and non-hospitalized patients, 211 unrelated hyperlipidemic patients were recruited for genotyping. CYP3A4 genotypes were determined by means of polymerase chain reaction and restriction fragment length polymorphism analysis. Of the non-hospitalized hyperlipidemic patients, 8 with CYP3A4*1/*1 and 8 with CYP3A4*1/*4 genotypes were selected to be treated with 20 mg simvastatin daily for 4 weeks. Serum triglycerides (TG), cholesterol (CHO) and low-density lipoprotein (LDL) levels were determined using an automated analyzer (Hitachi 747, Boehringer Mannheim, Mannheim, Germany). CYP3A4 activity was determined by the ratio of 6-hydroxycortisol to free cortisol (6-OHC/FC) in the morning spot urine with a high-throughput liquid chromatography-tandem mass spectrometry method.

RESULTS

Of 211 subjects, 14 (allele frequency 3.32%) were heterozygous for CYP3A4*4 (Ile118Val). Nevertheless, no subjects with a CYP3A4*5 or CYP3A4*6 allele or homozygous for CYP3A4*4 were identified. The ratio of 6beta-OHC/FC was 9.9 +/- 13.7 and 56.6 +/- 35.7 in subjects with the Ile118Val variant (n = 8) and in CYP3A4 wild-type subjects (n = 8), respectively (P = 0.0039). After oral intake of simvastatin 20 mg daily for 4 weeks, the change of serum lipids in CYP3A4*1/*1 and CYP3A4*1/*4 groups showed a significant difference, with a mean decrease in triglycerides and total cholesterol of 38.1 +/- 7.6% versus 25.1 +/- 8.3% (P = 0.034) and of 35.8 +/- 9.6% versus 22.0 +/-20.4% (P = 0.0015) (means +/- SD), respectively. We found no statistically significant difference in the reductions of LDL between subjects carrying the *1 and *4 genotypes (29.0 +/- 7.4% versus 36.8 +/- 8.8%, P = 0.0721).

CONCLUSIONS

The allele frequency of CYP3A4*4 was 3.32% among the hyperlipidemic patients from the Chinese mainland. CYP3A4*4 was an allelic variant related to a functional decrease of CYP3A4 activity, and *4 expression seemed to increase the lipid-lowering effects of simvastatin.

Pharmacokinetics of citalopram in relation to genetic polymorphism of CYP2C19

The study was designed to define the contribution of cytochrome p450 2C19 (CYP2C19) and cytochrome p450 3A4 (CYP3A4) to citalopram N-demethylation and to evaluate the relationship between the disposition of citalopram and CYP2C19 genotype. A single oral 40-mg dose of citalopram was administered to eight extensive metabolizers and five poor metabolizers recruited from 77 healthy Chinese volunteers whose genotypes and phenotypes were predetermined. The plasma concentrations of citalopram and desmethylcitalopram were determined by high-performance liquid chromatography. It was found that the genotype of CYP2C19 had a significant effect on the N-demethylation of citalopram. Poor metabolizers with m1 mutation had higher area under the plasma concentration versus time curve (AUC0--> infinity ) values than did extensive metabolizers. Terminal elimination half-life (t1/2) values of citalopram in poor metabolizers were significantly higher than the values in extensive metabolizers who were either homozygous or heterozygous with CYP2C19*1. The oral clearance (CLoral) of citalopram in poor metabolizers was significantly lower than that of extensive metabolizers. The AUC0--> infinity and maximum plasma concentration (Cmax) of desmethylcitalopram in poor metabolizers were significantly lower than the values of extensive metabolizers. The results show that CYP3A4 is not the major enzyme in the N-demethylation of citalopram among extensive metabolizers. The polymorphism of CYP2C19 plays an important role in the N- demethylation of citalopram in vivo. The extensive metabolizers and poor metabolizers of CYP2C19 had significant difference in disposition of citalopram in vivo.

The incidence of fracture among patients with inflammatory bowel disease. A population-based cohort study

BACKGROUND

The clinical significance of the high prevalence of osteopenia in inflammatory bowel disease is unclear.

OBJECTIVE

To determine whether persons with inflammatory bowel disease have increased incidence of fracture.

DESIGN

Population-based matched cohort study.

SETTING

Manitoba, Canada.

PATIENTS

Patients with inflammatory bowel disease in the University of Manitoba IBD Database (n = 6027) were matched to 10 randomly selected persons in the general population without inflammatory bowel disease (n = 60 270) by year, age, sex, and postal area of residence.

MEASUREMENTS

The incidence of hospitalization for hip fracture was determined on the basis of hospital discharge abstracts. Outpatient medical billing records and hospital discharge abstracts were used to calculate the incidence of spine, rib, and forearm fractures. Rates were calculated on the basis of person-years of follow-up for 1984 to 1997.

RESULTS

Persons with inflammatory bowel disease had significantly increased incidence of fractures at the spine (incidence rate ratio [IRR], 1.74 [95% CI, 1.34 to 2.24]; P < 0.001), hip (IRR, 1.59 [CI, 1.27 to 2.00]; P < 0.001), wrist/forearm (IRR, 1.33 [CI, 1.11 to 1.58]; P = 0.001), and rib (IRR, 1.25 [CI, 1.02 to 1.52]; P = 0.03) and of any of these fractures (IRR, 1.41 [CI, 1.27 to 1.56]; P < 0.001).

CONCLUSION

The incidence of fracture among persons with inflammatory bowel disease is 40% greater than that in the general population.