Toward standardization of carbohydrate-deficient transferrin (CDT) measurements: II. Performance of a laboratory network running the HPLC candidate reference measurement procedure and evaluation of a candidate reference material

Recommendations on the measurement and use of the alcohol consumption biomarker CDT. A position paper from the IFCC Working Group on CDT standardisation

BACKGROUND

Carbohydrate deficient transferrin (CDT) is a biomarker for excessive alcohol consumption utilized in clinical and forensic medicine and workplace testing. Previously, many different analytical methods for CDT were used and the measurand varied considerably, making direct comparison of test results difficult. To end this confusion, the IFCC established a working group on CDT standardisation (WG-CDT) which completed its tasks in 2017.

METHODS

This IFCC position paper by the WG-CDT summarizes state of the art information about the measurand and the analytical methods and gives concise recommendations for its utilization.

RESULTS

The results achieved by the CDT standardisation process led to accuracy improvements in national external quality assessment schemes over the years. A brief review of ROC based comparison studies with the traditional biomarkers (GGT, MCV, ALT and AST) discusses the bias resulting from inadequate study populations. In large groups of the general population the superior diagnostic performance of CDT is confirmed.

CONCLUSION

The relationship between alcohol intake versus resulting CDT is discussed as well as the cutoff and measurement uncertainty. Concerning the application in practice, potential pitfalls are considered and recommendations handling both analytical and preanalytical caveats are given. Finally, some examples of serious misunderstandings in publications about CDT are addressed.

New evidence of high association between carbohydrate deficient transferrin (CDT) and alcohol-related road traffic accidents. A retrospective study on 929 injured drivers

BACKGROUND

It is well known that traffic injuries still represent one of the main causes of death and that high blood alcohol concentrations while driving significantly increase the occurrence of accidents. However, only limited literature on the correlation between chronic alcohol abuse and accident risk is available. The aim of the present study was to investigate the hypothesis of an association between elevated concentrations of carbohydrate deficient transferrin (CDT) and the occurrence of alcohol-related traffic accidents.

METHODS

The analytical determinations of BAC and CDT were performed following certified methods in HS-GC-FID and HPLC, respectively. For BAC, 0.50 g/L was used as cut-off, whereas 2.0% was used for CDT, according to the standardisation proposed by IFCC. A total of 929 drivers, tested for BAC at the time of hospital admission after a traffic accident, were classified into two groups: InjDr 1 (BAC ≤ 0.50 g/L) and InjDr 2 (BAC>0.50 g/L); all drivers were also tested for CDT.

RESULTS

InjDr 1 included 674 individuals, only 2.5% showing a CDT above the cutoff, whereas InjDr 2 group consisted of 255 subjects, 28.6% testing positive for CDT (Odds Ratio 15.5). When subdividing the InjDr group into increasing classes of CDT, a steady increase in the percentage of BAC-positive drivers was appreciated. Moreover, average BAC was found to parallel each class of CDT.

CONCLUSIONS

The reported data strongly support the use of CDT as a biomarker of increased risk of alcohol-related traffic accidents in the procedures of re-granting of the driving license upon confiscation for "drink driving".

Efficacy and comparative effectiveness of telephone and smartphone remote continuing care interventions for alcohol use disorder: a randomized controlled trial

BACKGROUND AND AIMS

Management of alcohol use disorder (AUD) could be enhanced by effective remote treatments. This study tested whether supplementing intensive outpatient programs (IOPs) with continuing care delivered via (1) telephone, (2) smartphone or (3) their combination improves outcomes relative to (4) IOP only. Continuing care conditions were also compared.

DESIGN

Randomized controlled trial of four groups with 3-, 6-, 9-, 12- and 18-month follow-ups.

SETTING

University research center in Philadelphia, PA, USA.

PARTICIPANTS

Participants (n = 262) met DSM-V criteria for AUD, were largely male (71%) and African American (82%).

INTERVENTIONS AND COMPARATOR

Telephone monitoring and counseling (TMC; n = 59), addiction comprehensive health enhancement support system (ACHESS; n = 68) and TMC + ACHESS (n = 70) provided for 12 months. The control condition received IOP only (TAU; n = 65).

MEASUREMENT

The primary outcome was percentage of days heavy drinking (PDHD) in months 1-12. Secondary outcomes were any drinking, any drug use, drinking consequences and quality of life.

FINDINGS

Mean PDHD in months 1-12 was 10.29 in TAU, 5.41 in TMC, 6.80 in ACHESS and 5.99 in TMC + ACHESS. PDHD was lower in TMC [Cohen's d = 0.35, P = 0.018, 95% confidence interval (CI) = (-1.42, -0.20)], ACHESS [d = 0.31, P = 0.031, 95% CI = (-1.27, -0.06)] and TMC + ACHESS [d = 0.36, P = 0.009, 95% CI = (-1.40, -0.20)] than in TAU. Differences between TMC + ACHESS, TMC and ACHESS were small (d ≤ 0.06) and non-significant. Findings were inconclusive as to whether or not the treatment conditions differed on PDHD at 18 months. A significant effect was obtained on any drinking, which was higher in months 1-12 in TAU than in TMC [odds ratio (OR) = 3.02, standard error (SE) = 0.43, 95% CI = (1.30, 6.99), P = 0.01] and TMC + ACHESS [OR = 2.43, SE = 0.39, 95% CI = (1.12, 5.27), P = 0.025). No other significant effects were obtained on other secondary outcomes during or after treatment.

CONCLUSIONS

A telephone-delivered intervention and a smartphone-delivered intervention, alone and in combination, provided effective remote continuing care for alcohol use disorder. The combination of both interventions was not superior to either alone and effects did not persist post-treatment.

Opioid and Dopamine Genes Interact to Predict Naltrexone Response in a Randomized Alcohol Use Disorder Clinical Trial

BACKGROUND

While the opiate antagonist, naltrexone, is approved for treating alcohol use disorder (AUD), not everyone who receives the medication benefits from it. This study evaluated whether the OPRM1 SNP rs1799971 interacts with the dopamine transporter gene DAT1/SLC6A3 VNTR rs28363170 or the catechol-O-methyltransferase (COMT) gene SNP rs4680 in predicting naltrexone response.

METHODS

Individuals who met DSM-IV alcohol dependence were randomly assigned to naltrexone (50 mg/d) or placebo based on their OPRM1 genotype (75 G-allele carriers and 77 A-allele homozygotes) and also genotyped for DAT1 VNTR (9 vs. 10 repeats) or COMT SNP (val/val vs. met carriers). Heavy drinking days (%HDD) were evaluated over 16 weeks and at the end of treatment. Effect sizes (d) for naltrexone response were calculated based on genotypes.

RESULTS

Naltrexone, relative to placebo, significantly reduced %HDD among OPRM1 G carriers who also had DAT1 10/10 (p = 0.021, d = 0.72) or COMT val/val genotypes (p = 0.05, d = 0.80), and to a lesser degree in those OPRM1 A homozygotes who were also DAT1 9-repeat carriers (p = 0.09, d = 0.70) or COMT met carriers (p = 0.03, d = 0.63). All other genotype combinations showed no differential response to naltrexone. Diarrhea/abdominal pain was more prominent in OPRM1 A homozygotes who were also DAT 9 or COMT met carriers.

CONCLUSIONS

These results suggest that individuals with AUD with a more opioid-responsive genotype (OPRM1 G carriers) respond better to naltrexone if they have genotypes indicating normal/less dopamine tone (DAT1 10,10 or COMT val,val), while those with a less responsive opioid-responsive genotype (OPRM1 A homozygotes) respond better to naltrexone if they have genotypes indicating greater dopamine tone (DAT1 9-repeat or COMT met carriers). These results could lead to more personalized AUD treatments.

Efficacy of Gabapentin for the Treatment of Alcohol Use Disorder in Patients With Alcohol Withdrawal Symptoms: A Randomized Clinical Trial

IMPORTANCE

Although an estimated 30 million people meet criteria for alcohol use disorder (AUD), few receive appropriate pharmacotherapy. A more personalized, symptom-specific, approach might improve efficacy and acceptance.

OBJECTIVE

To examine whether gabapentin would be useful in the treatment of AUD, especially in those with the most alcohol withdrawal symptoms.

DESIGN, SETTING, AND PARTICIPANTS

This double-blind randomized clinical trial conducted between November 2014 and June 2018 evaluated gabapentin vs placebo in community-recruited participants screened and treated in an academic outpatient setting over a 16-week treatment period. A total of 145 treatment-seeking individuals who met Diagnostic and Statistical Manual of Mental Disorders (Fifth Edition) criteria for AUD and were not receiving other AUD intervention were screened, and 96 who also met recent alcohol withdrawal criteria were randomized to treatment after 3 abstinent days. Daily drinking was recorded, and percentage of disialo carbohydrate-deficient transferrin in the blood, a heavy drinking marker, was collected at baseline and monthly during treatment.

INTERVENTIONS

Gabapentin up to 1200 mg/d, orally, vs placebo along with 9 medical management visits (20 minutes each).

MAIN OUTCOMES AND MEASURES

The percentage of individuals with no heavy drinking days and those with total abstinence were compared between treatment groups and further evaluated based on prestudy alcohol withdrawal symptoms.

RESULTS

Of 96 randomized individuals, 90 were evaluable (44 in the gabapentin arm and 46 in the placebo arm), with a mean (SD) age of 49.6 (10.1) years; 69 were men (77%) and 85 were white (94%). The evaluable participants had 83% baseline heavy drinking days (4 or more drinks/day for women, 5 or more for men) and met 4.5 alcohol withdrawal criteria from the Diagnostic and Statistical Manual of Mental Disorders (Fifth Edition). More gabapentin-treated individuals had no heavy drinking days (12 of 44 participants [27%]) compared with placebo (4 of 46 participants [9%]), a difference of 18.6% (95% CI, 3.1-34.1; P = .02; number needed to treat [NNT], 5.4), and more total abstinence (8 of 44 [18%]) compared with placebo (2 of 46 [4%]), a difference of 13.8% (95% CI, 1.0-26.7; P = .04; NNT, 6.2). The prestudy high-alcohol withdrawal group had positive gabapentin effects on no heavy drinking days (P < .02; NNT, 3.1) and total abstinence (P = .003; NNT, 2.7) compared with placebo, while within the low-alcohol withdrawal group, there were no significant differences. These findings were similar for other drinking variables, where gabapentin was more efficacious than placebo in the high-alcohol withdrawal group only. Gabapentin caused more dizziness, but this did not affect efficacy.

CONCLUSIONS AND RELEVANCE

These data, combined with others, suggest gabapentin might be most efficacious in people with AUD and a history of alcohol withdrawal symptoms. Future studies should evaluate sleep changes and mood during early recovery as mediators of gabapentin efficacy.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT02349477.

Nicotine-Use/Smoking Is Associated with the Efficacy of Naltrexone in the Treatment of Alcohol Dependence

BACKGROUND

The opioid antagonist naltrexone is not efficacious for every alcohol treatment seeker. However, various individual factors, such as genetic differences and nicotine-use/smoking status, have been suggested as predictors of naltrexone response. In a randomized clinical trial, we previously reported that nicotine-use/smoking status might be a stronger predictor of naltrexone efficacy than OPRM1 A118G single nucleotide polymorphism (SNP) genotype. In this report, we further characterize the nicotine-users in that trial, examine other drinking outcomes, examine the influence of smoking change on naltrexone effects on drinking, and validate the result in smokers with disialo carbohydrate-deficient transferrin (%dCDT) change as an independent biomarker of response.

METHODS

Individuals (n = 146) meeting DSM-IV criteria for alcohol dependence who were genotyped for the OPRM1 A118G SNP and who did, or did not, use nicotine/cigarettes were randomized, in a balanced fashion, to naltrexone (50 mg/d) or placebo and provided medical management (MM) over a 16-week clinical trial. Alcohol use and smoking during the trial were assessed and analyzed.

RESULTS

Nicotine-use/smoking status significantly interacted with medication in reducing percent heavy drinking days (PHDD) during the trial (p = 0.003), such that nicotine-users/smokers showed significantly lower PHDD on naltrexone versus placebo (p = 0.0001, Cohen's d = 0.89), while nonusers showed no significant difference between naltrexone and placebo (p = 0.95, Cohen's d = 0.02). Similar effects were shown for drinks per day and percent days drinking. The superiority of naltrexone over placebo on PHDD reduction in nicotine-users/smokers was confirmed with %dCDT (Cohen's d range 0.3 to 0.9 over the study). Naltrexone did not significantly change cigarette use in smokers, and change in use did not influence naltrexone's effect on PHDD.

CONCLUSIONS

These data confirm past findings that naltrexone is more efficacious in those who use nicotine/cigarettes. Compared to previous work on the OPRM1 A118G SNP, it appears that nicotine-use might be a more salient predictor of naltrexone treatment response. While naltrexone did not change cigarette use during the study, and smoking change was not related to alcohol reduction, it should be noted that participants were not seeking smoking cessation and MM did not address this issue.

Effects of automated smartphone mobile recovery support and telephone continuing care in the treatment of alcohol use disorder: study protocol for a randomized controlled trial

Background

New smartphone communication technology provides a novel way to provide personalized continuing care support following alcohol treatment. One such system is the Addiction version of the Comprehensive Health Enhancement Support System (A-CHESS), which provides a range of automated functions that support patients. A-CHESS improved drinking outcomes over standard continuing care when provided to patients leaving inpatient treatment. Effective continuing care can also be delivered via telephone calls with a counselor. Telephone Monitoring and Counseling (TMC) has demonstrated efficacy in two randomized trials with alcohol-dependent patients. A-CHESS and TMC have complementary strengths. A-CHESS provides automated 24/7 recovery support services and frequent assessment of symptoms and status, but does not involve regular contact with a counselor. TMC provides regular and sustained contact with the same counselor, but no ongoing support between calls. The future of continuing care for alcohol use disorders is likely to involve automated mobile technology and counselor contact, but little is known about how best to integrate these services.

Methods/Design

To address this question, the study will feature a 2 × 2 design (A-CHESS for 12 months [yes/no] × TMC for 12 months [yes/no]), in which 280 alcohol-dependent patients in intensive outpatient programs (IOPs) will be randomized to one of the four conditions and followed for 18 months. We will determine whether adding TMC to A-CHESS produces fewer heavy drinking days than TMC or A-CHESS alone and test for TMC and A-CHESS main effects. We will determine the costs of each of the four conditions and the incremental cost-effectiveness of the three active conditions. Analyses will also examine secondary outcomes, including a biological measure of alcohol use, and hypothesized moderation and mediation effects.

Discussion

The results of the study will yield important information on improving patient alcohol use outcomes by integrating mobile automated recovery support and counselor contact.

Trial registration

ClinicalTrials.gov, NCT02681406. Registered on 2 September 2016.

Electronic supplementary material

The online version of this article (10.1186/s13063-018-2466-1) contains supplementary material, which is available to authorized users.

Monitoring of transferrin isoforms in biological samples by capillary electrophoresis

Work dealing with the monitoring of transferrin isoforms in human serum and other body fluids by capillary electrophoresis is reviewed. It comprises capillary zone electrophoresis and capillary isoelectric focusing efforts that led to the exploration and use of assays for the determination of carbohydrate-deficient transferrin as a marker for excessive alcohol intake, genetic variants of transferrin, congenital disorders of glycosylation and β-2-transferrin, which is a marker for cerebrospinal fluid leakage. This paper provides insight into the development, specifications, strengths, weaknesses, and routine use of the currently known capillary electrophoresis based assays suitable to detect transferrin isoforms in body fluids. The achievements reached so far indicate that capillary zone electrophoresis is an attractive technology to monitor the molecular forms of transferrin in biological specimens as the assays do not require an elaborate sample pretreatment and thus can be fully automated for high-throughput analyses on multicapillary instruments. Assays based on capillary isoelectric focusing are less attractive. They require immunoextraction of transferrin from the biological matrix and mobilization after focusing if instrumentation with a whole-column imaging detector is not available. Interactions of the carrier ampholytes with the iron of transferrin may prevent iron saturation and thus provide more complicated isoform patterns.

Analytical and diagnostic aspects of carbohydrate deficient transferrin (CDT): A critical review over years 2007-2017

The need for investigating alcohol abuse by means of objective tools is worldwide accepted. Among the currently available biomarkers of chronic alcohol abuse, carbohydrate-deficient transferrin (CDT) is one of the most used indicator, mainly because of its high specificity. However, some CDT analytical and interpretation aspects are still under discussion, as witnessed by numerous research papers and reviews. The present article presents a critical review of the literature on CDT appeared in the period from 2007 to 2017 (included). The article is organized in the following sections: (1) introduction, (2) pre-analytical aspects (3) analytical aspects (4) diagnostic aspects (5) concluding remarks. As many as 139 papers appeared in the international literature and retrieved by the search engines PubMed, Web of Science and Scopus are quoted.

Relationship of Abnormal Chromatographic Pattern for Carbohydrate-Deficient Transferrin with Severe Liver Disease

AIMS

Serum carbohydrate-deficient transferrin (CDT) is a validated test for chronic heavy alcohol drinking, but CDT abnormalities have been associated with liver disease, limiting its use in these patients. We report here on the association between poor chromatographic resolution of disialotransferrin from trisialotransferrin (the so-called 'di-tri bridging') and liver disease severity and etiology.

METHODS

Subjects were patients in whom detailed clinical data, including histology results, were available on their existing liver diseases (n=139). Percent disialo-CDT (%dCDT) was measured by high-performance liquid chromatography, and the risks for di-tri bridging associated with cirrhosis, with and without adjustment for alcohol use and alcohol-related liver disease, were estimated.

RESULTS

Di-tri bridging was present in 22/73 (30%) cirrhotic subjects and 7/66 (11%) non-cirrhotic subjects. The unadjusted risk for di-tri bridging in cirrhotics relative to non-cirrhotics was 3.6 (95% confidence interval 1.4-9.2). Adjustment for alcohol-related liver disease and current drinking had little effect on this estimate (adjusted odds ratio 3.4), and neither alcohol-related liver disease nor current drinking were independently associated with di-tri bridging after accounting for the effect of cirrhosis.

CONCLUSIONS

The presence of di-tri bridging was associated with cirrhosis in individuals with both alcohol-related and non-alcoholic liver disease, although most cirrhotic subjects did not exhibit di-tri bridging. When di-tri bridging is seen in individuals being tested for chronic heavy drinking, investigation for cirrhosis should be considered.

SHORT SUMMARY

There are known liver-disease-associated abnormalities in CDT. In this study, we found that such abnormalities were strongly associated with cirrhosis rather than less-advanced disease, but were only clinically evident in 30% of cirrhotics. Abnormalities also occurred in severe hepatitis without cirrhosis and were not specific for liver disease etiology.

Harmonization of Measurement Results of the Alcohol Biomarker Carbohydrate-Deficient Transferrin by Use of the Toolbox of Technical Procedures of the International Consortium for Harmonization of Clinical Laboratory Results

BACKGROUND

The need for equivalent results of routine measurement procedures for the alcohol biomarker carbohydrate-deficient transferrin (CDT) has been recognized by the IFCC. This article describes a project to harmonize CDT as conducted by an IFCC working group initiated for this purpose.

METHODS

We used procedures for achieving harmonization as developed by the Consortium for Harmonization of Clinical Laboratory Results to assess the suitability of a candidate reference measurement procedure (cRMP), candidate reference materials (cRMs), and the success of efforts to achieve harmonization.

RESULTS

CDT measurement procedures in routine use showed good reproducibility (CV 1.1%–2.8%) and linearity (r &gt; 0.990) with variable slopes (0.766–1.065) and intercepts (−0.34 to 0.92) compared to the cRMP. Heterogeneity after simulated harmonization was 4.7%. cRMs of frozen human native sera demonstrated commutability and 3-year stability for routine measurement procedures. The cRMP provided reproducible value assignment to cRMs with an expanded uncertainty (k = 2) of 0.03% at the 1.2% CDT level and 0.06% at the 4.4% CDT level. Harmonization efforts reduced the intermeasurement CV from 8.8% to 3.4%, allowed 99% recovery of the values assigned with the cRMP, and demonstrated 99% of results within the desirable allowable total error. Harmonization was less successful in samples with low CDT and high trisialotransferrin concentrations.

CONCLUSIONS

Harmonization of CDT is possible with frozen human native sera as cRMs with values assigned by use of the cRMP. We propose the cRMP as a candidate international conventional reference measurement procedure and cRMs as candidate international calibrators.

Diagnostic sensitivity of carbohydrate deficient transferrin in heavy drinkers

Background and Aim

Carbohydrate deficient transferrin (CDT) is the most specific serum biomarker of heavy alcohol consumption, defined as ≥ 350–420 g alcohol/week. Despite introduction of a standardized reference measurement technique, widespread use of CDT remains limited due to low sensitivity. The aim of this study was to determine the factors that affect diagnostic sensitivity in patients with sustained heavy alcohol intake.

Methods

Patients with a self-reported history of sustained heavy alcohol consumption were recruited from the hepatology outpatient department or medical wards. Each patient was interviewed with a validated structured questionnaire of alcohol consumption and CDT analysis using the standardized reference measurement technique with high performance liquid chromatography was performed on serum collected at time of interview.

Results

52 patients were recruited: 19 from the hepatology outpatient department and 33 from general medical wards. Median alcohol intake was 1013 (range 366–5880) g/week over the preceding two week period. 26 patients had a diagnostic CDT based on a threshold value of %CDT > 1.7 indicating heavy alcohol consumption, yielding a sensitivity of 50%. Overweight/obesity (defined as body mass index (BMI) ≥ 25 kg/m² in Caucasians and ≥ 23.0 kg/m² in Asians), female gender and presence of cirrhosis were independently associated with non-diagnostic %CDT (≤ 1.7).

Conclusions

CDT has limited sensitivity as a biomarker of heavy alcohol consumption. Caution should be applied when ordering and interpreting %CDT results, particularly in women, patients with cirrhosis and those with an elevated BMI.

Comparative performance of biomarkers of alcohol consumption in a population sample of working-aged men in Russia: the Izhevsk Family Study

AIMS

To assess the performance of a range of biomarkers of alcohol consumption in a heavy-drinking population of working-aged Russian men.

DESIGN

Cross-sectional study of men originally sampled at random from a population register.

SETTING

Izhevsk, a Russian city with a population of 650 000 people.

PARTICIPANTS

A total of 1023 men aged 27-59 years living in Izhevsk who took part in a health check examination in 2008-2009.

MEASUREMENTS

Self-reported alcohol consumption, hazardous drinking behaviours, socio-economic position, anthropometric measurements plus blood levels of alcohol biomarkers [carbohydrate-deficient transferrin (CDT, gamma-glutamyl transferase (GGT), alanine aminotransferase (ALT), aspartate aminotransferase (AST) and mean cell volume of erythrocytes (MCV)] and hepatitis B and C status.

FINDINGS

In the year before interview there was a high prevalence of high-risk alcohol consumption indicated by consumption of non-beverage alcohols (5%), problem drinking behaviours (4.4%) and alcohol consumption exceeding an average 40 g per day (12.6%). All biomarkers were associated strongly with total beverage alcohol consumption even after adjustment for confounders. CDT performed best as an alcohol biomarker, with a sensitivity of 67% and specificity of 71% for detecting an average consumption of more than 40 g per day versus less. For all biomarkers sensitivity was considerably lower than specificity. Hazardous drinking patterns per se were not well detected by any of the biomarkers, all with sensitivity below 60%.

CONCLUSIONS

In a Russian population with high levels of alcohol consumption, carbohydrate-deficient transferrin (CDT) might be the most sensitive and specific biomarker for detecting ethanol consumption above 40 g/day. A biomarker reflecting hazardous drinking patterns has yet to be established.

BMI but not stage or etiology of nonalcoholic liver disease affects the diagnostic utility of carbohydrate-deficient transferrin

BACKGROUND

A reliable biomarker is required in hepatology clinics for detection and follow-up of heavy alcohol consumption. Carbohydrate-deficient transferrin (CDT) increases with sustained heavy alcohol consumption and is the most specific biomarker of ethanol (EtOH) consumption. Recent introduction of a standardized method for measuring CDT has improved its clinical application. This study was designed to determine whether alcohol-independent factors influence CDT levels in patients with chronic liver disease (CLD).

METHODS

The relationship between serum %CDT and self-reported history of alcohol consumption was examined in 254 patients referred for evaluation of liver disease. CDT analysis was performed on serum collected at time of liver biopsy.

RESULTS

CDT levels were not affected by severity or etiology of nonalcoholic liver disease. Thirteen of 254 subjects had a %CDT >1.7, predictive of heavy alcohol intake, 6 of whom did not acknowledge heavy drinking. Twelve of these 13 subjects were suspected heavy drinkers on review of their medical records and clinical results. Conversely, not all acknowledged heavy drinkers had %CDT >1.7. Heavy drinkers with a body mass index (BMI) in the overweight or obese range had significantly lower %CDT than lean heavy drinkers. This persisted even when lean body weight was used as an approximation of the EtOH volume of distribution.

CONCLUSIONS

An elevated BMI reduces the diagnostic utility of CDT at higher alcohol intake in subjects with CLD using the standardized method. In a hepatology outpatient setting, this assay is likely to be useful to confirm suspicion of heavy drinking in subjects who are not overweight, but cannot reliably identify moderate drinkers or heavy drinkers who are overweight.

Effect of transferrin glycation on the use of carbohydrate-deficient transferrin as an alcohol biomarker

AIMS

Measurement of an alcohol-induced shift in the serum transferrin glycosylation pattern, termed carbohydrate-deficient transferrin (CDT), is used as a biomarker for sustained high alcohol consumption. The present work examined whether non-enzymatic reaction of transferrin with glucose (glycation) might interfere with the use of CDT as an alcohol biomarker.

METHODS

The blood specimens were leftover volumes from the routine sample pool. Plasma and serum were collected among samples submitted for hemoglobin A1c (HbA1c) and CDT testing. Quantification of individual transferrin glycoforms in percentage of total transferrin was performed by an HPLC candidate CDT reference method.

RESULTS

Incubating serum spiked with 20 or 200 mmol/l glucose caused time- and dose-dependent changes in the chromatographic profile of transferrin glycoforms, resulting in gradually wider peaks and reduced relative amounts of disialo- and trisialotransferrin. No similar chromatographic effects were seen in samples collected from diabetic patients with elevated HbA1c (>68 mmol/mol) values. These samples instead showed slightly higher mean %disialotransferrin levels (1.21%) compared with low HbA1c (<44 mmol/mol) samples (mean 1.06%; P = 0.023), pointing at a higher alcohol consumption level in the former group. Altogether ∼5% of the CDT values exceeded the cutoff. There was no significant difference in phosphatidylethanol (PEth) levels between the high and low HbA1c samples, but several (∼14%) showed elevated PEth concentrations.

CONCLUSION

Glycation of serum transferrin in vivo was indicated to differ from that in vitro, and suggested not to interfere with %CDT testing by the HPLC method. The results indicated that CDT and PEth are useful as objective, complementary alcohol biomarkers to identify risky drinking also in diabetic subjects.

Advanced gestational age increases serum carbohydrate-deficient transferrin levels in abstinent pregnant women

AIMS

Carbohydrate-deficient transferrin (%CDT) is a well-established and highly specific biomarker for sustained heavy consumption of alcohol. However, in pregnant women, the specificity of this biomarker might be affected by advanced gestational age, even after accounting for increased transferrin concentrations in pregnancy. The goal of this prospective study was to assess the variability in %CDT during pregnancy among alcohol-abstaining patients.

METHODS

Patients were recruited during one of the first prenatal care visits and followed-up to term. Abstinence was confirmed by maternal self-report and by alcohol biomarkers. Biomarkers assessed in the mother included serum gamma-glutamyltranspeptidase, urine ethyl glucuronide and ethyl sulfate, and whole blood phosphatidylethanol (PEth). In addition, PEth was measured in a dry blood spot card obtained from a newborn. For %CDT analysis, serum samples were collected at baseline and at term and analyzed by an internationally validated high-performance liquid chromatography and spectrophotometric detection method.

RESULTS

At recruitment (mean gestational age 22.6 ± 7.3 weeks), the mean %CDT concentration was 1.49 ± 0.30%, while at term, it increased to 1.67 ± 0.28% (P = 0.001). Using a conventional cutoff concentration %CDT >1.7%, 22.9 and 45.7% of the sample would be classified as 'positive' for this biomarker at recruitment and at term, respectively (P = 0.011 ).

CONCLUSION

These results suggest that a conventional cutoff of 1.7% might be too low for pregnant women and would generate false-positive results. We propose that %CDT >2.0% be used as a cutoff concentration indicative of alcohol exposure in pregnant women. The sensitivity of %CDT at this cutoff for heavy drinking during pregnancy needs to be assessed further.

Disialo-trisialo bridging of transferrin is due to increased branching and fucosylation of the carbohydrate moiety

BACKGROUND

Carbohydrate deficient transferrin (CDT) is used for detection of alcohol abuse and follow-up. High performance liquid chromatography (HPLC) of transferrin glycoforms is highly specific for identification of alcohol abuse, but unresolved disialo- and trisialotransferrin glycoforms sometimes makes interpretation difficult. The cause of this phenomenon is unknown, cannot be explained by genetic variants of transferrin, but seems to be associated with liver disease.

METHODS

Nineteen serum samples showing di-tri bridging when analyzed by HPLC were collected. Transferrin was purified by affinity chromatography, and N-linked oligosaccharides were released enzymatically. The N-glycans were further analyzed by high performance anion-exchange chromatography with pulsed amperometric detection and MALDI-TOF mass spectrometry.

RESULTS

The HPLC-analysis showed three different types of glycoform patterns. The N-glycans from fifteen samples showed patterns with increased number of triantennary structures containing one or two fucose residues. One sample contained an increased amount of triantennary glycans without fucose. Three samples showed a glycosylation pattern similar to normal transferrin.

CONCLUSIONS

The di-tri bridging phenomenon was associated with alterations in transferrin glycosylation in the majority of cases. Transferrin contained a higher extent of triantennary and often fucosylated N-linked oligosaccharides. These results may be important in future diagnostic approaches to liver diseases.

Phosphatidylethanol (PEth) as a biomarker of alcohol consumption in HIV-positive patients in sub-Saharan Africa

BACKGROUND

Alcohol is heavily consumed in sub-Saharan Africa and affects HIV transmission and treatment and is difficult to measure. Our goal was to examine the test characteristics of a direct metabolite of alcohol consumption, phosphatidylethanol (PEth).

METHODS

Persons infected with HIV were recruited from a large HIV clinic in southwestern Uganda. We conducted surveys and breath alcohol concentration (BRAC) testing at 21 daily home or drinking establishment visits, and blood was collected on day 21 (n = 77). PEth in whole blood was compared with prior 7-, 14-, and 21-day alcohol consumption.

RESULTS

(i) The receiver operator characteristic area under the curve (ROC-AUC) was highest for PEth versus any consumption over the prior 21 days (0.92; 95% confidence interval [CI]: 0.86 to 0.97). The sensitivity for any detectable PEth was 88.0% (95% CI: 76.0 to 95.6) and the specificity was 88.5% (95% CI: 69.8 to 97.6). (ii) The ROC-AUC of PEth versus any 21-day alcohol consumption did not vary with age, body mass index, CD4 cell count, hepatitis B virus infection, and antiretroviral therapy status, but was higher for men compared with women (p = 0.03). (iii) PEth measurements were correlated with several measures of alcohol consumption, including number of drinking days in the prior 21 days (Spearman r = 0.74, p < 0.001) and BRAC (r = 0.75, p < 0.001).

CONCLUSIONS

The data add support to the body of evidence for PEth as a useful marker of alcohol consumption with high ROC-AUC, sensitivity, and specificity. Future studies should further address the period and level of alcohol consumption for which PEth is detectable.

Comparative evaluation of capillary zone electrophoresis and HPLC in the determination of carbohydrate-deficient transferrin

BACKGROUND

Transferrin (Tf) glycoform lacking one or two complete or incomplete glycan chains (i.e., asialo-monosialo- and disialo-Tf) typically appear in blood after chronic alcohol consumption, though recently it was reported that monosialo-Tf is associated with trisialo-Tf but not with alcohol consumption. These glycoforms are collectively known as carbohydrate-deficient transferrin (CDT). Since samples from alcoholic patients are characterized by decreased sialic acid content in serum transferrin, the assessment of CDT is thereby widely used for laboratory evaluation of chronic alcohol abuse.

METHODS

CDT analysis has been performed in 6011 consecutive subjects undergoing national mandatory testing after the confiscation of driving license for driving under the influence of alcohol. Out of the 6011 specimens, 539 (9%) displayed values exceeding the specific cut-off (>1.3%) on multicapillary electrophoresis (MCE) (Capillarys2 Sebia, France), and were further analyzed with a routine high-pressure liquid chromatography (HPLC) technique.

RESULTS

The overall correlation between the methods in the total 539 samples was satisfactory, displaying a correlation coefficient (r) of 0.960. Nevertheless, the correlation was lower in the group with CDT values comprised between 1.3% and 1.9% (group 1; r=0.60) than in those with CDT values >2.0% (group 2; r=0.98). Moreover, the discordance between values exceeding the method-specific threshold in the former group of samples was also remarkably high (62% of samples in group 1 vs. 0.6% in group 2). Finally, a significant difference of CDT values was observed in group 1 (p<0.001), and in group 2 (p<0.0001) by Wilcoxon test.

CONCLUSIONS

The MCE is characterized by a high throughput and it seems a suitable approach for laboratory monitoring of alcohol abuse when CDT is used as medical parameter in the diagnosis and follow-up of heavy drinking. However, CDT measured by screening techniques must be confirmed by a confirmatory technique, in particular for forensic purpose.