Prevalence Of Thiamine Deficiency Research Articles

Investigation of Whole Blood Thiamine Concentration in Independently Ambulatory Residents of a Provincial Town in Japan: A Cross-Sectional Study.

Background Thiamine deficiency (TD) is an important public health problem in nutrition, occurring in 2-6% of the population in Europe and the US, whereas thiamine levels are reported to be significantly reduced by 36.6-40% in some populations of East Asia. However, there is little information available at present, regarding factors such as age, despite the continued aging of society. Further, studies such as those mentioned above have not yet been undertaken in Japan, the country in which population aging is most advanced. Objective To investigate TD in the Japanese community-dwelling individuals who are independently ambulatory. Methods We undertook an examination of TD in blood samples obtained from 270 citizens in a provincial town, aged 25-97 years, who were able to walk to the venue and provide informed consent for inclusion in this researchand of whom 8.9% had a history of cancer. We summarized the demographic characteristics of the subjects. The whole-blood thiamine concentrations were measured using the high-performance liquid chromatography method. A value of 21.3 ng/ml or less was taken as low and a borderline value was set as less than 28 ng/ml. Results The mean (±SD) whole blood thiamine concentration was 47.6 ± 8.7 ng/ml. No TD was observed to exist participating in this study, with no subjects even showing show borderline values. Further, there was no significant difference in thiamine level between those aged 65 or older and those aged less than 65. Conclusions No cases of TD were observed among the subjects in this study, nor was the concentration of thiamine found to be related to age. It is possible that the frequency of TD might be very low in citizens who have a certain level of activity. In the future, it is necessary to expand the prevalence of TD to a wider range of subjects.

The prevalence of thiamine deficiency among elderly nursing home residents: A cross-sectional study.

Although thiamine deficiency (TD) can lead to Wernicke encephalopathy, the characteristics associated with TD in the elderly have not yet been clarified. We sought to clarify the frequency of TD among an institutionalized elderly population with a controlled dietary intake and to identify possible factors related to TD. We undertook a cross-sectional study of residents in three nursing homes for the elderly as of June 2020. Blood thiamine concentrations were measured using a high-performance liquid chromatography method, with TD defined as a concentration of <21.3ng/mL. Basic data (age, sex, height, weight, and BMI), dietary intake for the previous 3 weeks, degree of care (DOC), degree of independence in daily life for elderly with dementia (DIDLED), and comorbidities were analyzed using descriptive statistical methods. The mean age (±SD) was 86.9 years (±8.29), with 84 residents (70.0%) being female. The DIDLED varied from total independence to long-term care level 5 (full assistance), with 89.2% suffering dementia. The mean whole blood thiamine value was 36.18 (±17.58) ng/ml, with TD confirmed in 7 (5.8%) of the 120 residents. All TD patients suffered from dementia. No TD was observed in patients with a near-normal food intake, and no related factors were observed among the other items. Reduced food intake may at increase the risk of TD and symptoms of TD may be overlooked in those displaying symptoms of dementia; thus, it is important for clinicians working with the elderly to remain aware of the potential for TD.

Prevalence and Time Course of Thiamine Deficiency in Critically Ill Children: A Multicenter, Prospective Cohort Study in Turkey.

To determine the prevalence and time course of thiamine deficiency (TD) in PICU patients. Multicenter, prospective, cohort study between May 2019 and November 2019. Three university-based tertiary care, mixed medical-surgical PICUs in Ankara, Turkey. PICU patients 1 month to 18 years old. None. We studied 476 patients and grouped them by TD status on days 1 and 3 of the PICU admission. There might be a risk of unintended bias since we excluded 386 patients because of the absence of consent, inadequate blood samples, loss of identifier information, and recent vitamin supplementation. On day 1, TD was present in 53 of 476 patients (11.1%) and median (minimum-maximum) thiamine levels were 65.5 ng/mL (5-431 ng/mL). On day 3, TD was present in 27 of 199 patients (13.6%) with repeated measurement. The median (minimum-maximum) thiamine levels were 63 ng/mL (13-357 ng/mL). The time course of TD from day 1 to day 3 in these 199 patients was as follows. In 21 of 199 patients (10.6%) with TD on day 1, 11 of 21 (52%) continued to have TD on day 3 and the other 10 of 21 patients (48%) improved to no longer having TD. In 178 of 199 patients (89.4%) without TD on day 1, 16 of 178 (9%) went on to develop TD by day 3, and the other 162 of 178 (91%) continued to have normal thiamine status. In the PICU population in three centers in Turkey, the prevalence of TD in the sample of patients was 11.1%. In those TD patients who had serial studies, we also identified that by day 3 some continued to be TD, and some patients improved to normal thiamine status. Of concern, however, is the population who develop TD over the course of PICU stay.

Abstract 9983: Thiamine Deficiency is Associated with Longer Length of Stay and Higher Hospitalization Cost in Patients with Atrial Fibrillation

Introduction: Chronic thiamine deficiency (TD) can cause changes in the myocardium through cellular hypotrophy, which may lead to arrhythmias. Although animal models have not revealed major electrical remodeling, supraventricular tachyarrhythmias are associated with low thiamine levels. TD is associated with chronic alcohol and loop diuretic use. The prevalence of TD in patients with supraventricular arrhythmias is unknown. We assessed the prevalence of TD among patients hospitalized for atrial fibrillation (AF) using data from the National Inpatient Sample (NIS) database between 2005 to 2015. Hypothesis: TD is prevalent in individuals with a history of chronic alcohol use and is associated with worse in-hospital outcomes. Methods: Using ICD-9 codes, we queried the NIS for discharge encounters involving adults with AF. We compared the differences in baseline characteristics and in-hospital outcomes between those with and without a diagnosis of TD using the Chi-Square test and the Wilcoxon rank-sum test as two-tailed at a 5% level of significance. Results: Of the 38,283,200 discharge encounters, 0.02% had a diagnosis of thiamine deficiency (N = 7,287). TD was common among white males, younger patients, and those with a history of chronic alcohol use. TD did not affect inpatient mortality but was associated with a longer hospital stay and a higher cost of care (Table 1). Conclusions: Among hospitalized patients with AF, TD does not affect in-hospital mortality but is associated with increased length of stay and cost of care. Further investigation is necessary to assess the effect of thiamine supplementation on AF burden and response to rate or rhythm control.

Prevalence of Thiamine Deficiency in Chronic Heart Failure Patients: Ramathibodi Cardiology Clinic Experience

Objective: Thiamine deficiency is still a public health concern in developing countries including Thailand. Heart failure is associated with thiamine deficiency especially in patients receiving diuretic therapy. Therefore, we sought to find the prevalence of thiamine deficiency in chronic heart failure outpatients. Materials and Methods: A cross-sectional descriptive epidemiological study in 50 heart failure patients scheduled for regular follow-up visits at Ramathibodi Cardiology Clinic, Mahidol University, Bangkok, Thailand. Thiamine pyrophosphate effect was used to identify thiamine deficiency. Review of electrical medical records were made in order to collect variable clinical and demographic data. Results: The mean age was 60&plusmn;2.1 years, 54% were male. The mean left ventricular ejection fraction was 37&plusmn;2.5%. The prevalence of thiamine deficiency in a chronic heart failure outpatient was 6% (n=3). Thiamine status was negatively associated with left ventricular ejection fraction (r=-0.283, p=0.047) and thiamine status was positively associated with left ventricular dimension (r=0.462, p=0.001). However, there was no association between the dose of diuretic and thiamine status (r=0.024, p=0.882), duration of heart failure and thiamine status (r=-0.012, p=0.945). In patients with severe thiamine deficiency, there were subsequent serious adverse cardiovascular outcomes (one had cardiac arrest and underwent left ventricular assist device). Conclusion: We found that the prevalence of thiamine deficiency in chronic heart failure outpatients is low in an urban outpatient setting. Keywords: Thiamine deficiency; Heart failure; Prevalence

Prevalence of thiamine deficiency is significant in patients undergoing primary bariatric surgery.

Patients undergoing metabolic and bariatric surgery are prone to developing micronutrient deficiencies, necessitating life-long nutritional supplementation and monitoring. Historically, these deficiencies were thought to be driven by postsurgical changes in absorption. Recent data, though, have demonstrated that obesity alone is also associated with micronutrient deficiencies. Thiamine deficiency, in particular, can lead to permanent neurologic deficits. Identify thiamine deficiency prevalence within the preoperative metabolic and bariatric surgery patient population. Single institution academic medical center. A retrospective review of deidentified data was examined that included whole blood thiamine measured from consecutive patients from April 2018 to June 2019 (n = 346). Cohort characteristics were assessed including age, operation, preoperative weight, and race/ethnicity. The majority of the cohort were women (83%) with an average age of 44.9 years. Racial representation included White/Caucasian (73%) and Black (21%), while operations included Roux-en-Y gastric bypass (58%), sleeve gastrectomy (31%), and revisions (10%). Thiamine concentration was normally distributed with a mean of 144 nM. Overall, 3.5% of patients had thiamine concentrations below the lower limit of normal of <70 nM, while 35 additional patients (14%) were at risk for thiamine deficiency with concentrations <100 nM. On the average, these patients were of similar age and were all undergoing primary procedures (50% gastric bypass, 50% sleeve gastrectomy). Regression methods demonstrated that patients with thiamine deficiency tended to be females with higher body mass index, even after controlling for sex, height, and preoperative weight. After covariate adjustment, male sex and increasing height were both associated with higher thiamine concentration. Previously quoted rates of thiamine deficiency in the preoperative patient are variable, but we describe a significant number of patients with, or at risk of, thiamine deficiency. Male sex and increasing height are likely associated with increased skeletal muscle mass, which is enriched with thiamine. Routine thiamine measurement, either preoperatively or at the time of surgery, is warranted given its limited stores within the body and potential catastrophic complications associated with acute or chronic deficiency.

Thiamine deficiency in the outpatient psychiatric oncology setting: A case series.

B vitamins are essential for the functioning of the nervous system. Vitamin B1 (thiamine) deficiency is associated with neuropsychiatric syndromes such as Wernicke's encephalopathy (WE), which, if untreated, has an estimated mortality of 17-20%. Although the prevalence of thiamine deficiency in the general population is difficult to estimate, it is being increasingly recognized in oncology, especially in the inpatient setting. We describe three cases of thiamine deficiency (TD) in the outpatient psychiatric oncology setting. Retrospective chart review of three adult patients, who were seen in the psychiatric oncology clinic and found to have TD on laboratory testing, was done. Patient, disease, and thiamine treatment-related information were obtained, and descriptive statistics were used to analyze the data. The average age was 59 years, mean body mass index (BMI) was 22.00 ± 4.58 (mean ± SD), and mean thiamine level was 59.10 ± 7.69 that ranged from 45 to 68 nmol/L (normal thiamine level reference: 70-180 nmol/L). None of the patients had brain imaging nor cerebrospinal fluid analysis. Risk factors such as unbalanced nutrition, prior GI surgery, renal disease, and chemotherapy were noted. TD can have a multifactorial etiology in oncology. Identification of TD in both inpatient and outpatient setting is important. Our report highlights how early identification of TD in the outpatient setting can help prevent further clinical progression.

Potential thiamine deficiency in elderly patients with gastrointestinal cancer undergoing chemotherapy .

Gastrointestinal cancer and its treatment using fluorouracil-based anticancer agents are risk factors for thiamine deficiency (TD). Therefore, we aimed to determine the prevalence of TD among elderly patients with gastrointestinal cancer undergoing chemotherapy. We retrospectively reviewed the medical records of 12 elderly patients with gastrointestinal cancers who underwent chemotherapy. Median serum thiamine level was 22.5ng/mL (range, 17-42ng/mL). Four patients (33.3%) exhibited TD (&lt;20ng/mL). We found that the prevalence of TD among elderly patients with gastrointestinal cancer undergoing chemotherapy was high. For these patients, careful monitoring of thiamine levels is warranted because TD may not produce overt clinical symptoms.

Prevalence of Thiamin Deficiency in Ambulatory Patients with Heart Failure

BackgroundThiamin is a required coenzyme in energy production reactions that fuel myocardial contraction. Therefore, thiamin deficiency (TD) may aggravate cardiac dysfunction in patients with systolic heart failure (HF). ObjectiveTo determine the prevalence of TD in ambulatory participants with HF as well as the relationships between thiamin status and HF severity, dietary thiamin intake, diuretic use, and circulating neurohormones. DesignA cross-sectional study comparing the prevalence of TD in ambulatory patients with HF with that of controls. Demographic, anthropometric, nutrition, medication use, and heart function data were collected from direct interviewing, questionnaires, and medical records. Blood samples were obtained to measure levels of neurohormones and assess TD. Participants/settingFifty age-matched control participants without HF and 100 outpatients with HF and reduced left ventricular function were recruited from clinics at St Michael’s Hospital, University Health Network and Mount Sinai Hospital, Toronto, Ontario, Canada, between September 2009 and February 2011. Main outcome measuresTo assess TD, erythrocyte thiamin pyrophosphate (TPP) was measured using high-performance liquid chromatography. TD was defined as TPP<6.07 μg/dL (180 nmol/L). Statistical analyses performedPrevalence rates were analyzed using χ2 test. Nonparametric statistics (Jonckheere-Terpstra, Kruskal-Wallis, Spearman’s correlation) were used to assess TPP levels in relation to HF severity, medication use and plasma concentrations of F2-isoprostanes, norepinephrine, and N-terminal pro-brain natriuretic peptide (NT-proBNP). ResultsThere was no significant difference in the prevalence of TD in outpatients with HF (6%) and controls (6%) (P=0.99). No relationship was found between heart function, thiamin intake, use or dose of diuretics, and TD. A positive relationship was observed between erythrocyte TPP and F2-isoprostane levels (rs=0.22, P=0.03) but not between erythrocyte TPP and norepinephrine (P=0.45) and NT-proBNP (P=0.58). ConclusionThe prevalence of TD was low in ambulatory HF participants suggesting that, unlike hospitalized patients, ambulatory patients may be at a low risk for TD.

Role of Thiamin in Health and Disease.

Thiamin is a hydrosoluble vitamin that plays a role in several biological processes, mainly in glucose metabolism. There are several risk factors for developing thiamin deficiency, such as malnutrition, refeeding syndrome, gastrointestinal surgery, and alcoholism. Recently, the role of thiamin in critically ill patients has gained prominence, and the prevalence of thiamin deficiency was found to be increased in patients with severe burns, major surgery, septic shock, end-stage renal disease, and heart failure. In adults, thiamin deficiency presents as encephalopathy, dry beriberi (with neurological signs and symptoms), or wet beriberi (with cardiovascular signs and symptoms). Thiamin deficiency can be diagnosed clinically, and all clinicians should be aware of this disease, especially in patients with risk factors for thiamin deficiency. Thiamin supplementation should be started as early as possible in patients suspected to have thiamin deficiency. Treatment is safe, inexpensive, simple, and life-saving. Diagnosis is confirmed on a positive response to treatment.

Prevalence of thiamine deficiency in older hospitalized patients.

PurposeDespite some reports of high prevalence of thiamine deficiency in elderly people, the reported prevalence is controversial mainly due to the methods used in assessing thiamin concentrations. In this study, we sought to investigate the prevalence of vitamin B1 deficiency, using the high-performance liquid chromatography (HPLC) method, among older hospitalized patients.Patients and methodsThis cross-sectional study retrospectively analyzed the results of routine measurements of vitamin B1 of 238 older patients who were consecutively hospitalized to a geriatric acute care ward. Whole blood vitamin B1 concentrations were measured using the HPLC method at hospital admission, and the whole blood vitamin B1 level of <20 ng/mL was considered as deficiency.ResultsOf 238 patients, with a mean age of 82.1±7.1 years, 63% of patients were women. In total, the mean whole blood vitamin B1 level was 66.1±24.8 ng/mL (range 29.5–215 ng/mL), indicating no vitamin B1 deficiency in the entire population. In addition, no significant differences in the mean whole blood vitamin B1 concentrations between sexes were observed (P=0.356).ConclusionThis study indicates that the mean whole blood vitamin B1 concentrations using the HPLC method were within the normal range in older hospitalized patients suggesting that thiamine deficiency appears to be rather uncommon among these patients.

High rate of thiamine deficiency among inpatients with cancer referred for psychiatric consultation: results of a single site prevalence study.

Thiamine deficiency (TD) is increasingly recognized in medically ill patients. The prevalence of TD among cancer patients is unknown. This study aims to characterize the prevalence of TD among inpatients with cancer. Retrospective chart review of patients admitted to a large cancer center who were referred for psychiatric consultation and whose serum thiamine concentration was measured. Patients with alcohol use were excluded. Among 217 patients with various cancer types, TD was found in 55.3%. Risk factors included fluorouracil-based chemotherapy, significant weight loss, and undergoing active cancer treatment. Almost all patients were normal weight, overweight, or obese, and few had concomitant vitamin B12 or folate deficiency. A total of 17.5% were receiving multivitamin supplementation. Nearly half (49.8%) did not receive empiric treatment with thiamine and among those who did, treatment delay occurred in the majority of cases (59.6%). Measurement of serum thiamine concentration preceded psychiatric consultation in only 10.6% of cases. Our findings suggest that TD is highly prevalent among inpatients with cancer, even among normal and overweight individuals, in the absence of other vitamin deficiencies, and while receiving multivitamin supplements. Several potential risk factors were identified, including active cancer treatment. Evaluation of TD was most commonly not initiated by oncologists. Failure to treat and treatment delay were common. Given these findings, oncologists must be vigilant about detecting TD among inpatients with cancer. Copyright © 2016 John Wiley & Sons, Ltd.

Influence of intravenous thiamine supplementation on blood lactate concentration prior to cardiac surgery: A double-blinded, randomised controlled pilot study.

Stress related to surgery and critical illness depletes thiamine, essential in energy metabolism, and might result in high blood lactate concentrations and higher mortality. We hypothesised that thiamine supplementation would increase blood concentration of thiamine and reduce blood lactate concentration postoperatively. Moreover, we aimed to identify the prevalence of, and risk factors for, high blood lactate concentrations. This was a double-blind, randomised controlled pilot study from February to July 2012 including 30 patients scheduled for cardiac surgery with cardiopulmonary bypass. Patients were assigned randomly to receive thiamine (300 mg in 0.9% Normal saline solution) or placebo (0.9% Normal saline) preoperatively. One arterial blood sample was taken preoperatively and another postoperatively to measure thiamine concentration, and multiple samples were taken during surgery and ICU stay to determine lactate concentrations. Twenty-four hour urine samples were collected to measure urinary thiamine concentration. Preoperatively, we assessed extracellular mass to body cell mass ratio (ECM/BCM). The mean (SD) age of the patients was 58 (12) years, 73% were overweight, 10% were malnourished and the prevalence of thiamine deficiency was 10%. Patients in the thiamine group had significantly higher blood thiamine concentrations 2 days postoperatively [805.2 ± 289.8 ng g(-1) haemoglobin (Hb)] than those in the placebo group (591.2 ± 100.7 ng g(-1) Hb, P < 0.01). The mean blood lactate concentration changed significantly over time, but did not differ significantly between the groups. Patients with ECM/BCM more than 1 had higher lactate concentrations on admission to ICU than those with ECM/BCM less than 1 (2.1 ± 0.7 vs. 1.7 ± 0.6, P = 0.09) and were at a significantly greater risk of having a higher lactate concentration on ICU admission [odds ratio (OR) 13.5, 95% confidence interval (95% CI) 1.0 to 179.4, P < 0.05]. On the basis of these results, a sample size calculation for a larger study has been facilitated. Thiamine supplementation caused normalisation of blood and urine concentrations postoperatively but without a significant reduction in lactate concentration or clinical outcome. Body composition played an important role in lactate formation. Further research focusing on preoperative screening and optimal treatment of high lactate concentrations in this specific population is warranted. Clinicaltrials.gov identifier: NCT01524315.

Risk of thiamine deficiency and Wernicke’s encephalopathy after gastrointestinal surgery for cancer

Cancer patients submitted to gastrointestinal surgery are at risk of thiamine deficiency (TD) and Wernicke's encephalopathy (WE). Although permanent neurological damage and death could be prevented by a timely replacement therapy, they often remain undiagnosed and untreated. We hypothesized that WE remains unrecognized because most cases may manifest several months after hospital discharge. WE frequency was investigated in a sample of cancer patients who underwent gastrointestinal surgery, by using the diagnostic criteria proposed to improve diagnosis among alcoholics. Patients were evaluated at discharge through the examination of medical records and 6 months after by telephonic interview. Forty-five patients were selected. Signs of WE resulted in 4.4% at discharge. At 6 months, 21 patients were interviewed. Among them, 90.4% had signs of WE. The number of affected patients was significantly higher 6 months after discharge than at discharge (90.4 vs 9.5%, p < 0.0001). Further studies with larger samples are needed to establish the prevalence of TD and related WE in cancer patients after gastrointestinal surgery. This study suggests that the problem is understated. Even in absence of symptoms of TD, the use of prophylactic thiamine supplementation should be taken in consideration, as consequences of misdiagnosis can be severe.

Prevalence of thiamine deficiency in heart failure patients on long-term diuretic therapy

Background: Loop diuretics are an integral part of heart failure management. It has been shown that loop diuretics cause thiamine deficiency (TD) by increasing its urinary loss. The aim of this study was to determine the prevalence of TD in heart failure patients on long-term oral loop diuretics. Methods: Heart failure patients (cases) on oral loop diuretics (furosemide ≥40 mg/day or torsemide ≥20 mg/day), irrespective of the cause of heart failure, were compared to non-heart failure patients (controls) not on loop diuretics in a 1:1 ratio. Whole blood free thiamine level was determined by liquid chromatography-tandem mass spectrometry method. Results: A total of 100 subjects were enrolled in a 1:1 ratio (50 cases and 50 controls). 67% of the total study population had TD, (defined as whole blood free thiamine level <0.7 ng/ml). There was no difference in mean thiamine level between cases and controls. On comparing patients with TD in both groups, patients on diuretics had significantly lower thiamine level compared to the patients, not on diuretics (P < 0.0001). Conclusions: There was no difference in the thiamine level when patients on loop diuretics were compared to controls. However, very low thiamine levels (<0.1 ng/ml) was significantly more common in patients on loop diuretics.

Beriberi Outbreak among Myanmar and Thai workers in a Factory in Chachoengsao Province, Thailand, 2012-2013

Beriberi is a clinical syndrome which develops from prolonged severe thiamine deficiency in diet. In July 2013, the Ministry of Public Health, Thailand received reports of three deaths among Myanmar workers in a factory. We identified suspect beriberi cases, reviewed clinical history and conducted a survey among both Myanmar and Thai workers in the factory. Blood thiamine levels were measured and foods served in the factory canteen were also examined. Seventeen suspect cases (attack rate = 17%) were identified, with median age of 26 years (range 20-30 years) and male to female ratio of 3.3:1. All fatalities were young men (case fatality proportion = 17.6%). Prevalence of thiamine deficiency among Myanmar and Thai workers were 7.1% (95% CI = 0-22.0) and 26.7% (95% CI = 1.3-52.0) respectively. This outbreak was likely to be caused by long exposure to low thiamine intake and heavy physical activities. After distributing thiamine supplements and improving diet, no more cases occurred. We recommended improving hospital staff’s ability to differentiate beriberi from other cardiomyopathies and neurologic diseases, and raising awareness of thiamine deficiency in this area.

Thiamin deficiency and heart failure: the current knowledge and gaps in literature.

The management of heart failure (HF) represents a significant challenge for both patients as well as the healthcare system in industrialized countries. Thiamin is a required coenzyme in the energy-producing reactions that fuel myocardial contraction. Therefore, thiamin deficiency (TD) may contribute to myocardial weakness by limiting the energy available for contraction. Previous studies have reported a wide range in the prevalence of TD in patients with HF (3-91%). The impact of thiamin supplementation in patients with HF is inconclusive. Studies conducted to date are limited by their small sample size, indirect methods of assessing thiamin concentration, methodological inconsistencies, use of impractical means of thiamin supplementation, a focus on hospitalized patients, and lack a robust technique for the assessment of cardiac function. Future large prospective studies and randomized controlled trials are needed to improve our understanding of any change in nutritional requirements associated with chronic disease as well as the clinical benefit of supplementation.

648 Prevalence of Thiamin Deficiency in Ambulatory Patients With Systolic Heart Failure

648 Prevalence of Thiamin Deficiency in Ambulatory Patients With Systolic Heart Failure

Letters to the editors

Dear Sirs, Mayxay et al. (2007) recently reported that thiamin deficiency (erythrocyte transketolase activity coefficient, α > 1.31) occurs in 12% of 349 patients admitted with uncomplicated malaria, and may contribute to malaria-associated acidosis. Forty-two days after malaria chemotherapy and thiamin supplementation, the prevalence of thiamin deficiency had declined to 3%. As the authors correctly pointed out, it cannot be determined whether this improvement in thiamin status was a consequence of recovery from malaria or thiamin supplementation, or both. In their Figure 1, Mayxay et al. (2007) show that the percentage change in α between admission and day 42 and the α measured at admission were correlated. According to their interpretation, these data suggest that the improvement in thiamin status depends on the degree of thiamin deficiency at baseline. Scatter plot of the percentage change in a between admission a and day 42 and admission a in a computer simulation of 349 persons with random variation in erythrocyte ketolase activity coefficient, a. Two values [coordinates: (0.41; 156.0) and (0.52; 127.5)] that are outside the scale of the graph have been omitted. Relating change with baseline values, however, gives misleading results and consequently incorrect conclusions because of mathematical coupling and regression-to-the-mean effects (Hayes 1988; Tu et al. 2002; Verhoef & West 2005). To show this, the author has used a simulation whereby considering a fictitious population with α values that were normally distributed, with means and SDs as estimated from Figure 1 from the study by Mayxay et al. (2007). The author has used PQRS software (version 3.2; Knypstra 2003) to draw two independent random samples (n = 349) from normally distributed data with means and SDs as described above, and paired the resulting data to compute the change in simulated α values. The results show that the change in α value was negatively related to the baseline values (Figure 1). Such a result is to be expected because, if we have any two sets of random numbers, α0 and α1, and if we plot (α1−α0) on the y-axis and α0 on the x-axis, a negative relation will be observed. This is because −α0 occurs in the y-term and +α0 in the x-term. Regression to the mean occurs because of both measurement errors in α0 and heterogeneity of individual changes in α. Several methods have been proposed to rectify this problem (Tu & Gilthorpe 2007). When using these methods, Mayxay et al. (2007) may find that there is no evidence for the relationship reported.

Thiamine level in the elderly patients with heart failure

Purpose: Although thiamine deficiency has been reported to occur in patients with heart failure (HF), there were few reports regarding the prevalence of thiamine deficiency in elderly HF patients. Method: Blood thiamine and other clinical parameters were measured in patients with compensated (n = 22) and uncompensated (n = 23) HF. As a control, thiamine were measured from patients without HF (n = 12). Results: There was no difference in thiamine level among the three groups (compensated HF: 36.0 ± 2.8 ng/ml, decompensated HF:37.3 ± 3.4, control: 40.3 ± 6.9: normal range: 20–50 ng/ml: mean ± SE). However, more than 15% of patients among three groups were under normal range (compensated HF: 17.4%, decompensated HF: 18.2%, control: 16.7%). Thiamine level in patients with HF were not depend on the dose of the diuretics. Only one patient had apparent beriberi heart failure, whose thiamine level was lowest in all patients (10 ng/ml). Conclusion: To make diagnosis of beriberi heart failure depending solely on the blood thiamine level could be misleading in elderly patients. Evaluation of the response to VitB1 supplement and clinical findings such as peripheral neuropathy could be also important.