酒精性肝病的流行病学及自然史

酒精性肝病(ALD)是由于大量饮酒所致的肝脏疾病,初期通常表现为肝细胞内的脂肪沉积,进而可发展成洒精性肝炎、酒精性肝纤维化和酒精性肝硬化,在严重酗酒时可诱发广泛肝细胞坏死,甚至肝功能衰竭~([1]).在西方国家,酒精性肝病是肝硬化的主要病因之一.随着生活水平的提高,我国酒或含酒精饮料的消耗量大量增加,ALD的发病率与患病率也逐渐上升.在世界范围内,青少年嗜酒的比率也在不断增加,ALD已经成为全球性的公共卫生问题.酗酒所造成的社会危害及酒精相关疾病特别是ALD的高发,给国民经济带来沉重的压力,也是目前学术界研究的热点.现将系统性回顾国内外近年来在ALD的流行病学与转归方面所做的研究.     

The natural history of childhood-onset asthma.

A knowledge of the natural history of asthma in first years of life is necessary to establish preventive and therapeutic plans. The aim of this study was to overview the clinical evidence about the natural history of asthma in different pediatric ages, with emphasis on risk factors and prediction indexes. We used the data source PubMed, using a search algorithm selecting for natural history studies of asthma and respiratory allergy in all children to August 2005. A few studies prospectively assessed the natural history of asthma from infancy to childhood to adulthood to mature age. Some risk factors from these studies can be translated into prognostic indexes. The accuracy of such indexes seems skewed toward screening rather than diagnostic ability. Natural history is the basis on which accurate predictors of the persistence of wheezing and asthma can be predicated. In the absence of genetic markers, parental history of asthma, personal history of eczema, and immunologic tests such as serum IgE, peripheral eosinophilia, and serum eosinophilic cationic protein are the better indicators of the development of asthma in infants.     

Blastocystis hominis: epidemiology and natural history

To study the demographic profile of Blastocystis hominis carriers from Hamilton, Canada, the Regional Parasitology Laboratory records for 1988 were reviewed, and a prospective study on carriers was conducted to clarify the natural history of the infection and ascertain the role of B. hominis as an intestinal pathogen. Retrospective analysis revealed that 8% of stool samples harbored B. hominis. The median age of the carriers was 37 years; 55% were female. Prospective analysis of 139 patients showed that most (76%) of 86 in whom B. hominis was the sole organism found (and for whom data were complete) continued to harbor the parasite in stool samples submitted a median of 57 days after the first sample. There was no correlation between the presence of B. hominis and symptoms. Thus, B. hominis, though commonly seen in stool samples submitted to this laboratory, is thought to be a commensal organism.     

Hepatitis B: epidemiology and natural history

Chronic infection with hepatitis B and its sequelae remains a major global health concern. Despite recommendations and implementation of vaccination programs, the health and economic burdens are still significant. People in endemic areas and immigrants from these areas need to be adequately screened and treated. HBeAg-negative chronic hepatitis is increasingly recognized with additional challenges in management. Programs implementing primary prophylaxis strategies such as vaccination of high-risk adult and adolescent groups should continue.     

The changing epidemiology and natural history of hepatitis C virus infection

Injection drug use remains the predominant mode of transmission of hepatitis C virus (HCV) infection. Growing numbers of persons who have been chronically infected with HCV for 20 or more years are coming to medical attention and are at risk for serious complications of chronic infection, including cirrhosis and hepatocellular carcinoma. Factors linked with the development of advanced fibrosis and cirrhosis include age at infection, duration of infection, heavy alcohol use, coinfections with HIV or hepatitis B virus, and male sex. Emerging risk factors for disease progression include steatosis, insulin resistance (and factors associated with the metabolic syndrome), and host genetics.     

Allergic rhinitis: epidemiology and natural history.

Establishing a reliable estimate of the prevalence of allergic rhinitis is difficult; prevalence estimates range from as low as 4% to more than 40%. Epidemiology studies suggest the prevalence of allergic rhinitis in the United States and around the world is increasing. The cause of this increase is unknown; however, contributing factors may include higher concentrations of airborne pollution, rising dust mite populations, less ventilation in homes and offices, dietary factors, and the trend toward more sedentary lifestyles. Allergic rhinitis symptoms typically begin in childhood and adolescence and continue into adulthood. In general, allergic rhinitis symptoms slowly improve and skin-test reactivity tends to wane with increasing age. There is a significant trend for symptom improvement with younger age of onset of allergic rhinitis. As the complicated etiology of allergic rhinitis becomes better understood, it may be possible to reverse the trend for increased prevalence.     

Definition, epidemiology and natural history of COPD.

Chronic obstructive pulmonary disease (COPD) is the fifth cause of morbidity and mortality in the developed world and represents a substantial economic and social burden. Patients experience a progressive deterioration up to end-stage COPD, characterised by very severe airflow limitation, severely limited and declining performance status with chronic respiratory failure, advanced age, multiple comorbidities and severe systemic manifestations/complications. COPD is frequently underdiagnosed and under-treated. Today, COPD develops earlier in life and is less gender specific. Tobacco smoking is the major risk factor for COPD, followed by occupation and air pollution. Severe deficiency for alpha(1)-antitrypsin is rare; several phenotypes are being associated with elevated risk for COPD in the presence of risk factor exposure. Any patient presenting with cough, sputum production or dyspnoea should be assessed by standardised spirometry. Continued exposure to noxious agents promotes a more rapid decline in lung function and increases the risk for repeated exacerbations, eventually leading to end-stage disease. Without major efforts in prevention, there will be an increasing proportion of end-stage patients who can live longer through long-term oxygen therapy and assisted ventilation, but with elevated suffering and huge costs. Smoking prevention and smoking cessation are the most important epidemiological measurements to counteract chronic obstructive pulmonary disease epidemics.     

Consequences of long-term inflammation. The natural history of asthma

Although asthma is classically defined as reversible airflow obstruction, and often remits in younger subjects with milder disease, the natural history of asthma is that various degrees of airflow obstruction may persist and, in the long-term, asthma may become moderately to fully irreversible. Severe, irreversible airflow obstruction may develop despite apparently appropriate therapy and in the absence of other risk factors, such as smoking and environmental insults. All studies of subjects with persisting asthma show increased decline in lung function compared with normal subjects. Persistent abnormal physiology is reflected both in reduced airflow rates and in increased airway responsiveness. The cellular and molecular mechanisms of airway remodeling are described elsewhere in this issue. Questions not yet clearly answered are the reasons for these persistent abnormalities in some asthmatics, and which subjects are most at risk. Factors that adversely impact the outcome as adults identified relatively consistently among many longitudinal studies of the natural history of asthma include: Female gender. Environmental tobacco smoke exposure in childhood. Personal tobacco smoking in adolescence and adulthood. Age of onset of symptoms. Severity of childhood asthma. Duration of asthma. Severity of lung function abnormality in childhood. Bronchodilator reversibility. Degree of airway hyperresponsiveness. Delay in initiating anti-inflammatory therapy. Remission among adult asthmatics is uncommon, but is associated with better initial lung function, young age, male gender, and lesser degrees of airway responsiveness. The role of atopy remains controversial. Conversely, risk factors for death from asthma include older age, smoking, atopy, impaired lung function, and moderate to high reversibility. Treatment can improve lung function, reduce airway responsiveness, and improve quality of life. The overall effect of treatment on the natural history of the disease is not yet clear, despite significant short-term improvements from effective anti-inflammatory therapy.     

Heterogeneity of endoscopy negative heartburn：Epidemiology and natural history

It has now become clear that only about 40% or less of patients with heartburn and/or regurgitation have esophagitis, and that the majority of them lack visible distal esophageal mucosa breaks. These subjects are referred to as non-erosive gastroesophageal reflux disease （NERD） patients. It has been estimated that in the Western world at least one tenth of the general population has at least weekly heartburn. This proportion seems to be lower in Asia, while prevalence is rapidly increasing. Although it would be extremely useful to have prospective information regarding the fate of such patients, the natural history of NERD is largely unknown, and very few studies in the literature have addressed this issue. These studies are for the greater part old, not well conducted, and suffer from methodological drawbacks including ill-defined entry criteria. However, a review of these studies indicates that a consistent minority of NERD patients may develop erosive disease at an approximate rate of about 10% per year     

Gender differences in IgE-mediated allergic asthma in the epidemiology and natural history of asthma: Outcomes and Treatment Regimens (TENOR) study.

BACKGROUND: The TENOR study consists of a large cohort of subjects with severe or difficult-to-treat asthma. The objective of this analysis was to evaluate demographic and clinical characteristics of subjects 12 years of age or older with immunoglobulin E (IgE)-mediated allergic asthma (skin test positive with an IgE level = 30 to =700 IU/mL), and specifically, to assess gender differences in this cohort. METHODS: A total of 4,756 subjects were enrolled by 283 US study sites between January and October 2001. Of those subjects 12 years or older at baseline with an IgE measure and who were skin tested (n = 2,843), 1,783 (63%) were skin test positive and had an IgE level between = 30 to = 700 IU/mL. RESULTS: Compared to males, females reported significantly greater healthcare utilization (steroid bursts in previous 3 months: 50% vs 42%, p < 0.001; unscheduled office visits in previous 3 months: 50% vs 36%, p < 0.0001; missed 1+ days of work/school in previous 2 weeks: 14% vs 10%, p < 0.01). Females also reported significantly more asthma control problems and lower asthma-related quality of life (4.6 +/- 1.3 vs 5.2 +/- 1.2; p < 0.0001); the difference was clinically meaningful. Asthma triggers and allergic comorbidities, such as allergic rhinitis and atopic dermatitis, were more common in female subjects. Despite their overall worse health outcomes, female subjects demonstrated better lung function, had similar treatment patterns, and showed no differences in physician-assessed asthma severity when compared with males. CONCLUSIONS: The reasons for these gender differences in subjects with IgE-mediated allergic asthma are complex, but results from this analysis suggest that detailed evaluations of asthma patients, including symptom-related questions and asthma-related healthcare utilization, are needed to accurately assess asthma severity and control.     

Gallbladder polyps: epidemiology, natural history and management.

Polypoid lesions of the gallbladder affect approximately 5% of the adult population. Most affected individuals are asymptomatic, and their gallbladder polyps are detected during abdominal ultrasonography performed for unrelated conditions. Although the majority of gallbladder polyps are benign, most commonly cholesterol polyps, malignant transformation is a concern. The differentiation of benign from malignant lesions can be challenging. Several features, including patient age, polyp size and number, and rapid growth of polyps, are important discriminating features between benign and malignant polyps. Based on the evidence highlighted in this review, the authors recommend resection in symptomatic patients, as well as in asymptomatic individuals over 50 years of age, or those whose polyps are solitary, greater than 10 mm in diameter, or associated with gallstones or polyp growth on serial ultrasonography. Novel imaging techniques, including endoscopic ultrasonography and enhanced computed tomography, may aid in the differential diagnosis of these lesions and permit expectant management.     

Idiopathic pulmonary fibrosis: Diagnosis,epidemiology and natural history

Idiopathic pulmonary fibrosis (IPF) is a chronic, progressive fibrosing lung disorder of unknown aetiology whose diagnosis involves the careful exclusion of secondary causes for pulmonary fibrosis and the presence of a pattern of usual interstitial pneumonia (UIP) at either high‐resolution computed tomography (HRCT) scan or surgical lung biopsy. Despite great efforts made in establishing precise, universally acknowledged diagnostic criteria for IPF, its ascertainment remains a challenge, especially in those individuals presenting with atypical HRCT patterns. With new drugs emerging, establishing a precise diagnosis is becoming a clinically relevant issue. Although regarded as a rare disease, IPF epidemiology is controversial due to studies relying on old data and adopting mixed, incomparable methodologies for cases definition. Overall, the prevalence and incidence appear to be increasing over the last decades, suggesting that in earlier studies they might have been underestimated because of diagnostic uncertainty. IPF is invariably progressive, although its clinical course might greatly vary on an individual basis, with episodes of severe acute respiratory deterioration (acute exacerbations) being unpredictable. A deeper understanding of the mechanisms responsible for an accelerated course of the disease and the identification of biomarkers of progression would lead to a better stratification of the disease, essential for delivering individualized therapeutic strategies.     

The natural history, epidemiology, and prognosis of heart failure in African Americans

Heart failure is more common in African Americans and appears to be of worse severity. At the time of diagnosis, left ventricular function is more severely impaired and the clinical class is more advanced. The strongest risk factor for heart failure in African Americans appears to be hypertension, which is both more prevalent and more pathologic in African Americans. It is likely that heart failure represents an important end organ effect of hypertension. When affected by heart failure, African Americans experience a greater rate of hospitalization and may be exposed to a higher mortality risk as well. Genomic medicine has yielded a number of candidate single nucleotide polymorphisms that might contribute to the excess pathogenicity of heart failure in African Americans, but much more work needs to be done in larger cohorts. Effective therapy of heart failure must start with the recognition of the different manifestations of heart failure in African Americans. An increased awareness of the risk of hypertension followed by early and effective intervention may reduce the risk of heart failure in this population.     

Primary sclerosing cholangitis: epidemiology, natural history, and prognosis

Primary sclerosing cholangitis is a progressive disease associated with significant morbidity and mortality that continues to draw attention from investigators worldwide. Epidemiologic studies indicate that its annual incidence remains stable, although more asymptomatic cases are being diagnosed. Nevertheless, even asymptomatic cases can progress to end-stage liver disease, albeit at a highly variable rate. Moreover, patients are predisposed to several malignancies, especially cholangiocarcinoma, which contributes to their decreased survival. On the other hand, a subgroup of patients with the so-called small-duct variant may have a better prognosis, and those with overlap syndromes with autoimmune hepatitis may respond well to immunosuppressants. Otherwise, efficient treatment is not available for patients with primary sclerosing cholangitis. Thus, even though it occurs rarely, this disease is commonly an indication for liver transplantation. Fortunately, transplantation outcomes are excellent, with overall 5-year survival rates of approximately 80%.     

Disease definition, clinical manifestations, epidemiology and natural history of GERD

Gastro-esophageal reflux disease is a global problem and affects children, adolescents and adults. The incidence of the disease appears to be increasing particularly in Asia where reflux disease has not traditionally been a major health problem in the past. Recent consensus efforts to define and classify the disease in both adults and children make it possible to obtain epidemiologic and natural history data using a universally acceptable definition and classification.