Assessment of knowledge of celiac disease among health care professionals

Objectives:

To assess knowledge of celiac disease among medical professionals (physicians).

Methods:

We conducted a cross-sectional survey of hospital-based medical staff in primary, secondary, and tertiary care public, and private hospitals in Riyadh, Saudi Arabia (KSA). We carried out the study between January 2013 and January 2104 at King Khalid University Hospital, King Saud University, Riyadh, KSA. A pretested questionnaire was distributed to the potential participants. A scoring system was used to classify the level of knowledge of participants into 3 categories: poor, fair, and good.

Results:

A total of 109 physicians completed the survey and of these participants, 86.3% were from public hospitals, and 13.7% from private hospitals; 58.7% were males. Of the physicians, 19.2% had poor knowledge. Interns and residents had fair to good knowledge, but registrars, specialists, and even the consultants were less knowledgeable of celiac disease.

Conclusion:

Knowledge of celiac disease is poor among a significant number of physicians including consultants, which can potentially lead to delays in diagnosis. Educational programs need to be developed to improve awareness of celiac disease in the health care profession.Celiac disease (CD) is an autoimmune disorder that is triggered by ingestion of gluten in genetically susceptible individuals. This leads to small intestinal villous atrophy and its ensuing complications. Celiac disease is a common disorder, and the prevalence seems to be on the rise. The exact prevalence of CD in the Middle East and Saudi Arabia (KSA) is not known, but it affects approximately 0.5-1% of the general population in the West.1 The classical presentation of CD is in early childhood with a mal-absorptive picture leading to diarrhea and failure to thrive. However, many cases now present in adulthood. It can also have a variety of non-intestinal presentations such as anemia, fatigue, bone disease, liver enzyme elevation, and infertility.1,2 Highly sensitive screening tests such as immunoglobulin (Ig)A-tissue transglutaminase antibody are now available to screen for CD. The diagnosis of CD is confirmed with small intestinal biopsies, and treatment consists of a strict gluten-free diet for life.3 Health care professionals need to be aware of both the classical and non-classical (extra-intestinal) manifestations of CD in order to make a timely diagnosis. Delays in diagnosis can lead to potentially serious complications such as osteoporosis and small intestinal lymphoma.4 The purpose of the study was to assess the knowledge of CD among the medical professionals. The information obtained will help to design and conduct educational and training programs on CD.     

Clinical utility of dabigatran in United Arab Emirates: A pharmacovigilance study

Objectives:

To provide early data regarding clinical utility of dabigatran in Al-Ain, United Arab Emirates (UAE).

Methods:

This was an ethics approved retrospective cross sectional study. We retrieved a total of 76 patients who were using dabigatran from September to December 2014 in the Cardiology Clinic at Al-Ain Hospital, Al-Ain, UAE. The primary analysis was designed to test the frequency of bleeding events (rate) with dabigatran 75, 110, and 150 mg.

Results:

The mean age ± standard deviation of cohort was 67.9 ± 1.5 years (range; 29-98 years), composed of males (52.6%) with mean age of 66.3 ± 1.7 years, and females (47.4%) with mean age of 69.6 ± 1.1 years. The highest age group was those between 61-80 years (60.5%). Most comprised the age strata of ≤75 years (73.7%). The main indication for dabigatran use was atrial fibrillation. The rate of bleeding with dabigatran was 18/76 (23.7%), and melena was the leading cause of bleeding 8/76 (10.7%). The hospitalization rate was 67.1%, dabigatran withdrawal rate was 0.01%, and mortality rate was 6.5%. The cohort had exhibited incidences of minor bleeding with one fatal major bleeding, high co-morbidities, admission, and readmission, which was not directly linked to dabigatran. We did not identify any relation of death due to dabigatran.

Conclusion:

Dabigatran is a suitable alternative to warfarin obviating the need for repetitive international normalized ratio monitoring, however, it may need plasma drug monitoring.Atrial fibrillation (AF) is the most common cardiac arrhythmia that affects 1-1.5% of population worldwide.1 Atrial fibrillation prevalence increases with age, and rises from 0.7% in those between 55-59 years to 17.8% in those ≥85 years. Nearly 85% of patients with AF are aged >65 years old.2 The lifetime risk for the development of AF as demonstrated in the Framingham study was one in 4 for men and women aged ≥40 years,3 which pose certain concerns in countries with aging populations.4,5 In addition to this, hospitalization related to AF is alarmingly increasing.6 The risk of stroke in patients with AF is 5 folds, and systemic thromboembolism is 3 folds.7,8 Banerjee, et al9 has deployed stroke prevention score in patients with AF, however, the predictive value is of less magnitude. The European Society of Cardiology set estimation of stroke risk in patients with AF as per CHA₂DS₂-VASc score to determine the recommendation for initiating an oral anticoagulant,10 whereas in patients with CHA₂DS₂-VASc ≥2, HAS-BLED score can be used to assess the risk of bleeding, and commencement of anticoagulant.11Warfarin (vitamin K antagonist [VKA]) has proven efficacy in reducing the risk of stroke in patients with AF, however, it poses high bleeding incidences, emergency hospitalizations, unpredictable therapeutic effect, and multiple international normalized ratio (INR) tests leading to many limitations in its clinical utility.12 Novel oral anticoagulants (NOACs) are proved as effective anticoagulants in prevention of stroke in patients with AF. Novel oral anticoagulants were preferred in non-valvular AF, and do not require coagulation monitoring, however, strict adherence to approved indication is highly warranted.13 Dabigatran (Pradaxa^®), a competitive inhibitor of thrombin was approved in October 2010 by the United States of America Food and Drug Administration to reduce the risk of stroke, and systemic embolism in patients with non-valvular AF.14 A systematic review incorporated 6 economic reviews from diverse healthcare systems (USA, Canada, and United Kingdom) utilizing different economic models. It has suggested the benefit of dabigatran in patients with high-risk of stroke, high-risk of intra-cerebral hemorrhage, or suboptimal use of warfarin. The review outlined concerns on tolerability of dabigatran, adherence issues, and adverse consequences.15In comparison with warfarin, dabigatran 150 mg has shown low rates of stroke, and systemic embolism (dabigatran p<0.001 for superiority). However, both drugs exhibited comparable rates of major hemorrhage.16-18 Greater fatal, and non fatal bleeding events were reported with dabigatran than warfarin.19,20 A recent (2015) retrospective Medicare data analysis study20 on dabigatran’s safety highlighted that the incidence of bleeding was higher than with warfarin (33% versus 27%), major bleeding (9% versus 6%), and gastrointestinal bleeding (17% versus 10%). Intracranial hemorrhage occurred more often with warfarin than dabigatran (1.8% versus 0.6%).20 It has been documented that risks of major bleeding from dabigatran is high for patients with chronic kidney disease, and in African Americans.20 The Randomized Evaluation of Long-term Anticoagulant Therapy: Dabigatran versus warfarin-RE-LY studies18 have showed similar risk of bleeding with warfarin versus dabigatran in patients with non-valvular AF. This dictated the importance of age sub-group analysis in studies. In real clinical practice, patients from different countries may have more co-morbid conditions than those in the RE-LY study.21 The current available data around bleeding incidences from dabigatran is relevant to populations with diverse characteristics. Revealing the clinical utility of dabigatran in our Emirati population may demonstrate different perspectives. Therefore, we intend to provide early data around the clinical utility of dabigatran in United Arab Emirates (UAE) Emirati population.     

Birth prevalence of non-syndromic orofacial clefts in Saudi Arabia and the effects of parental consanguinity

Objectives:

To describe the characteristics and prevalence of non-syndromic orofacial clefting (NSOFC) and assess the effects of parental consanguinity on NSOFC phenotypes in the 3 main cities of Saudi Arabia.

Methods:

All infants (114,035) born at 3 referral centers in Riyadh, and 6 hospitals in Jeddah and Madinah between January 2010 and December 2011 were screened. The NSOFC cases (n=133) were identified and data was collected through clinical examination and records, and information on consanguinity through parent interviews. The diagnosis was confirmed by reviewing medical records and contacting the infants’ pediatricians. Control infants (n=233) matched for gender and born in the same hospitals during the same period, were selected.

Results:

The prevalence of NSOFC was 1.07/1000 births in Riyadh, and 1.17/1000 births overall; cleft lip (CL) was 0.47/1000 births, cleft lip and palate (CLP) was 0.42/1000 births, and cleft palate (CP) was 0.28/1000 births. Cleft palate was significantly associated with consanguinity (p=0.047, odds ratio: 2.5, 95% confidence interval: 1 to 6.46), particularly for first cousin marriages.

Conclusion:

The birth prevalence of NSOFC in Riyadh alone, and in the 3 main cities of Saudi Arabia were marginally lower than the mean global prevalence. While birth prevalence for CLP was comparable to global figures, the CL:CLP ratio was high, and only CP was significantly associated with consanguinity.Non-syndromic orofacial clefting (NSOFC), including isolated cleft lip (CL), cleft lip and palate (CLP), and isolated cleft palate (CP), is the most common craniofacial defect worldwide with an estimated mean global prevalence of 1.25/1000 live births.1 However, the prevalence of NSOFC varies geographically and across different ethnic groups.2 Although the ethnicity of the Middle East is considered Caucasian,3,4 geographically it is located between 3 continents (Asia, Africa, and Europe), which makes it unique and, in reality, a mixture of 3 ethnicities. A small number of studies have measured the prevalence of NSOFC in Saudi Arabia and neighboring countries with the reported prevalence ranging from 0.3 to 2.19/1000 births,5-9 and a mean value for all studies of 1.25/1000 births.10 In addition, consanguineous relationships have been suggested to increase the prevalence of congenital anomalies.11 These were also reported to be associated with NSOFC in a meta-analysis carried out on 16 studies that assessed the relationship between NSOFC and paternal consanguinity.12 Saudi Arabia, one of the largest countries in the Middle East, has a high rate of consanguineous marriage that varies between regions.13 Riyadh, which is the capital city of Saudi Arabia with a population of approximately 7.5 million and birth prevalence of 38,000/year,14,15 has a consanguinity marriages prevalence of 60%.16 The aims of this study were to 1) describe the characteristics and prevalence of NSOFC (CL, CLP, and CP) in Riyadh (the capital city in the central region of Saudi Arabia), 2) describe the prevalence of NSOFC phenotypes, and 3) the relationship between these and consanguinity in Saudi Arabia.     

Health care services provided to type 1 and type 2 diabetic patients in Saudi Arabia

Objectives:

To assess health care services provided to type 1 and type 2 diabetic patients and diabetes health care expenditure in the Kingdom of Saudi Arabia (KSA).

Methods:

This study was part of a nationwide, household, population based cross-sectional survey conducted at the University Diabetes Center, College of Medicine, King Saud University, Riyadh, Kingdom of Saudi Arabia between January 2007 and December 2009 covering 13 administrative regions of the Kingdom. Using patients’ interview questionnaires, health care services data were collected by trained staff.

Results:

A total of 5,983 diabetic patients were chosen to assess health care services and expenditure. Approximately 92.2% of health services were governmental and the remaining 7.8% were in private services. The mean annual number of visits to physicians was 6.5±3.9 and laboratories was 5.1±3.9. Diabetic patients required one admission every 3 years with a mean admission duration of 13.3±28.3 days. General practitioners managed 85.9% of diabetic cases alone, or shared with internists and/or endocrinologists. Health care expenditure was governmental in 90% of cases, while it was personal in 7.7% or based on insurance payment in 2.3%.

Conclusion:

Health services and its expenditure provided to diabetic citizens in Saudi Arabia are mainly governmental. Empowerment of the role of both the private sector and health insurance system is badly needed, aside from implementing proper management guidelines to deliver good services at different levels.The health care system (HCS) in the Kingdom of Saudi Arabia (KSA) is growing at an annual rate of 2% to meet the increasing demand for health care services caused by increased population growth, and a surge in chronic non-communicable diseases.1 This has resulted in an increase in the total health care budget by more than 2 times; from 30 billion Saudi Riyals (SR) (US$8 billion) in 2008 to approximately SR69 billion (US$18.4 billion US dollars) in the year 2011 with a cumulative allocation of SR113 billion (U$30.13 billion) in 2010 and 2011; which accounted for 3.7% of the estimated country’s gross domestic product (GDP), which is one of the highest among Gulf Cooperation Council (GCC) countries.2 The Saudi health care system, which is ranked 26th among 190 countries by the World Health Organization (WHO),3 has a lower percentage of average expenditure in relation to the country’s GDP than many developed and developing countries.4 The government HCS in KSA is structured to deliver free health care services to Saudi citizens through various public hospitals and primary health care centers (PHCCs) including government health sectors, such as the Ministry of Health (MOH), Military Health Services and University Health Institutions. In addition to this, the private health care sector, through its clinics and hospitals, provided 31.1% of the total health care services in KSA in 2013.5 The real challenge facing the Kingdom’s HSC is the increased demands for hospital beds and medical personnel to meet international standards.6 The population ratio of physician and nurses in the Kingdom is lower than the global ratio being 9.4 physicians and 21 nurses per 10,000 of population versus 13 physicians and 28 nurses globally.7 This explains the current imbalance between the growth in HCS and the real medical needs of Saudi citizens.Diabetes mellitus, being the most prevalent chronic non-communicable disease in the Kingdom, has a significant effect on the country’s HCS and overall economy.8,9 This is proved by the fact that 25.4% of Saudi citizens older than 30 years of age have diabetes, which implies that there are approximately 1.5 million Saudi citizens suffering from this chronic disease.10 This is aside from the fact that more than 70% of known diabetic patients in the Middle Eastern countries have poorly controlled diabetes,11 associated with high rates of chronic complications that place greater pressure on health services and expenditure, where in 2013, it was estimated that the Middle East and North Africa (MENA) region spent US$13.6 billion on diabetes care with the spending per person with diabetes, where the spending in Saudi Arabia was US$934, which is far below other GCC such as United Arab Emirates (US$2,228), Qatar (US$2,199), and Kuwait (US$1,886),12 although we strongly believe that these figures are underestimated.Diabetic patients are currently managed at all health care levels, from primary to secondary and tertiary levels by general practitioners (GPs), internists, and endocrinologists.13 Since diabetes care involves many medical disciplines, such as ophthalmology, cardiology, nephrology and so forth, specialized diabetes clinics, and diabetes centers are needed to function as liaising bodies. Although health care needs for diabetic patients’ management at a global level have witnessed a clear shift to the primary from secondary and tertiary health care levels,14 diabetic patients in the Kingdom are still receiving services at secondary or even tertiary levels. Since there are no studies so far that have looked into the health care services provided to diabetic patients in KSA, the current study, as a part of the Saudi Abnormal Glucose Metabolism and Diabetes Impact (SAUDI-DM) survey,10 has investigated the current status of health care services provided to diabetic patients. This study aimed to assess the medical system providing care to diabetic patients, and methods of payment through a randomly selected cohort of diabetic patients at a country level.     

Evaluation of knowledge and behavior of workers in Prince Mohammed International Airport in Western Saudi Arabia regarding public health emergency measures applied during Hajj season 2014

Objectives:

To evaluate the knowledge and behavior of workers at a Saudi airport regarding public health emergency measures applied during Hajj season.

Methods:

This study is a cross-sectional study conducted at the Prince Mohammed International Airport in Al-Madinah Al-Munawwarah, Saudi Arabia between August and September 2014. Data were collected by semi-structured questionnaires during personal interviews. Non-random purposive sampling was conducted to target workers at higher risk of acquiring infection from travellers.

Results:

One hundred and eighty-six participants were recruited of whom 92.5% were males. The study participants were workers in 8 different sectors. Twenty-six percent of the participants were health workers. Non-health workers were more likely to be concerned on acquiring infection while working at the airport compared with health workers (p=0.023). The most commonly feared disease was Ebola viral disease (EBV) among 30% of health workers, and 47% of non-health workers. Approximately 47% of non-health workers reported no knowledge of the procedures implemented during public health emergencies. The proportion of participants who received public health related training among non-health workers was significantly lower compared with health workers (p<0.00001).

Conclusion:

More emphasis should be given to educating airport workers on the potential health threats at the airport. Specific guidelines for public health emergencies at the airport should be established and communicated with airport sectors.Airports are frontier gates where proper public health measures are likely to reduce the possibility of allowing the entrance of communicable disease to a country. According to the World Health Organization (WHO) International Health Regulations mandate WHO member states to ensure that every designated point of entry is equipped with staff and instruments enabling smooth movements of the travellers while maintaining appropriate public health measures.1 Maintaining such regulations is likely to enhance proper travellers’ movement during public health emergencies by reducing possible interference between application of preventive public health measures, and the ability of travellers to access the designated points of entry. Additionally, ensuring the application of public health measures might aid in preventing the occurrence of any public health emergencies. A public health emergency is defined as any situation with health consequences that are likely to overwhelm the community’s routine capability of addressing them. A health situation can be considered as an emergency if there is a risk due to timing, such as facing emerging diseases threats during Hajj season, scale, as with an overwhelming number of causalities, or due to the unpredictability of the situation. Defining the nature of potential public health emergencies is crucial to allow competent development of preparedness plans.2 Having a large number of passengers arriving at a particular point of entry during a limited time is a burden on the available health services. A meticulous state of readiness is required to respond to any risk of spreading a communicable disease. The state of readiness is maintained by several steps including preparation of staff, equipment, and buildings.3,4 The burden of not maintaining effective public health event response measures is aggravated if an epidemic is announced in a particular region of the globe where travellers form these areas are scheduled to arrive in the country. During the Hajj season of 2014, the Ebola Virus Disease (EVD), which is a viral hemorrhagic disease, was announced as an epidemic disease in Guinea, Liberia, and Sierra Leone in West Africa. Additionally, a localized spread of the virus was announced in certain areas of Nigeria.5 The Saudi Arabian government, as a preventive measure, decided to prevent citizens of EVD-affected countries from entering the country. However, nationals of Nigeria were exempt as no extended transmission of EVD was announced.6,7 Nonetheless, several procedures were applied to prevent the transmission of Ebola virus among thousands of Nigerian pilgrims arriving in the country. These measures were mainly related to exit screening of travellers in Nigeria,8 and entry screening at points of entry in Saudi Arabia. Additionally, the Ministry of Health in Saudi Arabia produced response plans for infectious diseases (Middle East Respiratory Syndrome [MERS] and EVD) to be implemented during Hajj.9 There are many potential sources of infectious disease transmission from a single infected individual. The presence of infected travellers, such as an EVD infection, on an aircraft increases the risk of transmitting infection to neighboring passengers and flight crew. Airport workers, such as ground workers handling cleaning of aircrafts and lavatories, are at risk of the infection, especially with the presence of spilled infectious materials. Airport workers handling the flow of passengers during busy times are at risk of acquiring infection such as immigration, customs, security, and healthcare workers. Therefore, all of these individuals have to be aware of the potential health threats at the airport, should be aware of preventive methods, how to use preventive methods, and know what to do when facing a public health emergency event in the airport. Prince Mohammed Airport (Al-Madinah, Saudi Arabia) workers’ level of knowledge of the potential health threat at the airport is currently not known. Additionally, the attitude and practice of the staff when a public health emergency is announced in the airport is not measured. The significance of this study stems from the ability to investigate the degree to which airport workers, at the time of dealing with travellers during Hajj season, were able to deal with potential urgent infectious cases, and to adhere to the relevant protective guidelines.     

Shared clinical decision making: A Saudi Arabian perspective

Objectives:

To determine preferences of patients regarding their involvement in the clinical decision making process and the related factors in Saudi Arabia.

Methods:

This cross-sectional study was conducted in a major family practice center in King Abdulaziz Medical City, Riyadh, Saudi Arabia, between March and May 2012. Multivariate multinomial regression models were fitted to identify factors associated with patients preferences.

Results:

The study included 236 participants. The most preferred decision-making style was shared decision-making (57%), followed by paternalistic (28%), and informed consumerism (14%). The preference for shared clinical decision making was significantly higher among male patients and those with higher level of education, whereas paternalism was significantly higher among older patients and those with chronic health conditions, and consumerism was significantly higher in younger age groups. In multivariate multinomial regression analysis, compared with the shared group, the consumerism group were more likely to be female [adjusted odds ratio (AOR) =2.87, 95% confidence interval [CI] 1.31-6.27, p=0.008] and non-dyslipidemic (AOR=2.90, 95% CI: 1.03-8.09, p=0.04), and the paternalism group were more likely to be older (AOR=1.03, 95% CI: 1.01-1.05, p=0.04), and female (AOR=2.47, 95% CI: 1.32-4.06, p=0.008).

Conclusion:

Preferences of patients for involvement in the clinical decision-making varied considerably. In our setting, underlying factors that influence these preferences identified in this study should be considered and tailored individually to achieve optimal treatment outcomes.Patients and physicians assume different and varying roles in the medical consultation process. This could determine the extent of involvement of the patient and the physicians in the clinical decision making process and patient care management. In one extreme, the physician assumes the responsibility of the clinical decision with no or very little joint deliberation with the patient. This is known as the “paternalistic” approach.1,2 In the other extreme, the informed medical decision approach means that the clinical decision is made by patients and potential others, including family members, after obtaining all needed medical information that could enable the patient to make on appropriate decision. This is known as the “consumerism” approach to clinical decision-making.3,4 Shared decision making is probably at the center of this spectrum, in which patients and physicians exchange information, discuss the details of the medical problems, explore available treatment options, and conclude together an agreed treatment plan.5 The provision of health care that is consistent with the preferences of patients may improve the patients’ satisfaction and health outcomes.6,7 The practice of shared clinical decision-making was encouraged as it respects patients’ autonomy, values, and commitment to the agreed health plan and continuity of care.8 The relevant literature shows that most patients prefer to be offered information on their medical conditions, available options of treatment, and future plan of care.1,3,9 However, the extent of the involvement of patients in the process of decision making is variable and influenced by issues related to the patients status of their illnesses, and types of decisions under consideration.10,11 Patients of younger age, women, and with higher levels of education have been found to prefer an active role and to share this process. In addition, preferences of patients may change with time and different stages of the sickness.11,12 The complexity of this process is further compounded by the fact that patient views and attitudes towards involvement in medical decision making are influenced significantly by certain underlying cultural aspects. This necessitates a sensitive and individual approach for each patient.13 This study aims to explore preferences of patients from Saudi Arabia regarding their involvement in medical decision making, and to explore factors that may affect these preferences.     

Incidence of venous obstruction following insertion of an implantable cardioverter defibrillator. A study of systematic contrast venography on patients presenting for their first elective ICD generator replacement.

AIMS: The number of implantable cardioverter defibrillator (ICD) implantations, as well as follow-up procedures such as generator exchanges, lead revisions and lead system upgrades, is ever-increasing. Lead revisions and implantation of additional leads require venous access at the site of the previous ICD implantation. The aim of our study was therefore to evaluate the incidence of venous obstruction after chronic transvenous ICD system implantation. METHODS AND RESULTS: One hundred and five consecutive patients admitted for their first elective ICD generator replacement were included. All patients underwent bilateral contrast venography and the images were analyzed by two attending radiologists. Venous obstruction was classified as moderate stenosis (50-75% diameter reduction), severe stenosis (>75%) or total occlusion. Venous obstruction of various degrees was found in 25% of the patients. Complete occlusion was found in 9%, severe stenosis in 6% and moderate stenosis in 10% of the patients. The incidence of venous obstruction was increased in patients with a pacemaker prior to the initial ICD system implantation (67%). No difference was found in patients with a single defibrillator lead compared with patients who had an additional superior vena cava (SVC) shocking coil. However, the presence of a second shocking coil in the SVC incorporated in a single ICD lead was associated with an increased incidence of venous obstruction. No difference was found between silicone and polyurethane insulated leads. CONCLUSION: This study shows that venous obstruction occurs relatively frequently after ICD implantation. Therefore, contrast venography should always be obtained if malfunction of a preexistent lead is suspected or a system upgrade is considered.     

Persistence of hepatitis B vaccine immunity in hemodialysis patients

Although the efficacy of hepatitis B vaccines in patients undergoing chronic hemodialysis (HD) treatment has been documented, the persistence of immunity in this population remains largely unknown. In this study we evaluated the persistence of hepatitis B vaccine immunity in HD patients. We followed 37 hepatitis B vaccinated HD patients (following a four-dose vaccination schedule of 40 mug injections intramuscularly in the deltoid muscle at 0, 1, 2, and 6 months) for up to one year to evaluate the persistence of immunity (as indicated by serum levels of hepatitis B surface antibody (anti-HBs) equal to or higher than 10 IU/L). One year after vaccination, 18.9% of patients had lost their anti-HBs (transient responders), while 81.1% still had detectable antibodies in the serum (persistent responders). From 81.1% of persistent responders 11.5% and 88.5% were weak and high responders, respectively. There was no significant difference between persistent and transient responders regarding age, sex, or nutritional factors. We did not find any factors that related to maintaining protective levels of anti-HBs in HD patients. It seems that an antibody titer above 100 IU/L following vaccination is necessary in order to maintain that level of antibody one year later.