The independent and joint risks of alcohol consumption, smoking, and excess weight on morbidity and mortality: a systematic review and meta-analysis exploring synergistic associations.

OBJECTIVE: Alcohol consumption, smoking, and excess weight independently increase the risk of morbidity/mortality. Less is known about how they interact. This research aims to quantify the independent and joint associations of these exposures across health outcomes and identify whether these associations are synergistic. STUDY DESIGN: The protocol for this systematic review and meta-analysis was pre-registered (PROSPERO CRD42021231443). METHODS: Medline and Embase were searched between 1 January 2010 and 9 February 2022. Eligible peer-reviewed observational studies had to include adult participants from Organisation for Co-Operation and Development countries and report independent and joint associations between at least two eligible exposures (alcohol, smoking, and excess weight) and an ICD-10 outcome (or equivalent). For all estimates, we calculated the synergy index (SI) to identify whether joint associations were synergistic. Meta-analyses were conducted for outcomes with sufficiently homogenous data. RESULTS: The search returned 26,290 studies, of which 98 were included. Based on 138,130 participants, the combined effect (SI) of alcohol and smoking on head and neck cancer death/disease was 3.78 times greater than the additive effect of each exposure (95% confidence interval [CI] = 2.61, 5.48). Based on 2,603,939 participants, the combined effect of alcohol and excess weight on liver disease/death was 1.55 times greater than the additive effect of each exposure (95% CI = 1.33, 1.82). CONCLUSION: Synergistic associations suggest the true population-level risk may be underestimated. In the absence of bias, individuals with multiple risks would experience a greater absolute risk reduction from an intervention that targets a single exposure than individuals with a single risk.

Current and Emerging Biomarkers and Imaging Modalities for Nonalcoholic Fatty Liver Disease: Clinical and Research Applications.

PURPOSE: Nonalcoholic fatty liver disease (NAFLD) is a metabolic disorder that frequently coexists with obesity, metabolic syndrome, and type 2 diabetes. The NAFLD spectrum, ranging from hepatic steatosis to nonalcoholic steatohepatitis, fibrosis, and cirrhosis, can be associated with long-term hepatic (hepatic decompensation and hepatocellular carcinoma) and extrahepatic complications. Diagnosis of NAFLD requires detection of liver steatosis with exclusion of other causes of chronic liver disease. Screening for NAFLD and identification of individuals at risk of end-stage liver disease represent substantial challenges that have yet to be met. NAFLD affects up to 25% of adults, yet only a small proportion will progress beyond steatosis to develop advanced disease (steatohepatitis and fibrosis) associated with increased morbidity and mortality. Identification of this cohort has required the gold standard liver biopsy, which is both invasive and expensive. The use of serum biomarkers and noninvasive imaging techniques is an area of significant clinical relevance. This narrative review outlines current and emerging technologies for the diagnosis of NAFLD, nonalcoholic steatohepatitis, and hepatic fibrosis. METHODS: We reviewed the literature using PubMed and reviewed national and international guidelines and conference proceedings to provide a comprehensive overview of the evidence. FINDINGS: Significant advances have been made during the past 2 decades that have enhanced noninvasive assessment of NAFLD without the need for liver biopsy. For the detection of steatosis, abdominal ultrasonography remains the first-line investigation, although a controlled attenuation parameter using transient elastography is more sensitive. For detecting fibrosis, noninvasive serum markers of fibrosis and algorithms based on routine biochemistry are available, in addition to transient elastography. These techniques are well validated and have been incorporated into national and international screening guidelines. These approaches have facilitated more judicious use of liver biopsy but are yet to entirely replace it. Although serum biomarkers present a pragmatic and widely available screening approach for NAFLD in large population-based studies, magnetic resonance imaging techniques offer the benefit of achieving high degrees of accuracy in disease grading, tumor staging, and assessing therapeutic response. IMPLICATIONS: This diagnostic clinical and research field is rapidly evolving; increasingly combined applications of biomarkers and transient elastography or imaging of selective (intermediate or high risk) cases are being used for clinical and research purposes. Liver biopsy remains the gold standard investigation, particularly in the context of clinical trials, but noninvasive options are emerging, using multimodality assessment, that are quicker, more tolerable, more widely available and have greater patient acceptability.

Emerging and Established Therapeutic Approaches for Nonalcoholic Fatty Liver Disease.

PURPOSE: Nonalcoholic fatty liver disease (NAFLD), more recently referred to as metabolic-associated fatty liver disease, refers to a disease spectrum ranging from hepatic steatosis to nonalcoholic steatohepatitis (NASH), fibrosis, and cirrhosis, associated with hepatic complications (including liver fibrosis, cirrhosis, and hepatocellular carcinoma) and extrahepatic complications (particularly cardiometabolic complications, including type 2 diabetes and cardiovascular disease). Treatment options include lifestyle interventions (dietary modification and physical activity programs) and pharmacologic interventions. Treatment aims should be broad, with a hepatic focus (to improve/reverse hepatic inflammation, fibrosis, and steatohepatitis), ideally with additional extrahepatic effects affecting metabolic co-morbidities (eg, insulin resistance, glucose dysregulation, dyslipidemia), causing weight loss and affording cardiovascular protection. NASH and fibrosis represent the main histopathological features that warrant treatment to prevent disease progression. Despite a paucity of established treatments, the array of potential molecular targets, pathways, and potential treatments is continually evolving. The goal of this article was to provide a narrative review summarizing the emerging and more established therapeutic options considering the complex pathophysiology of NAFLD and the important long-term sequelae of this condition. METHODS: The literature was reviewed by using PubMed, conference abstracts, and press releases from early-phase clinical studies to provide an overview of the evidence. FINDINGS: As understanding of the pathophysiology of NASH/NAFLD evolves, drugs with different mechanisms of action, targeting different molecular targets and aberrant pathways that mediate hepatic steatosis, inflammation, and fibrosis, have been developed and are being tested in clinical trials. Pharmacologic therapies fall into 4 main categories according to the molecular targets/pathways they disrupt: (1) meta-bolic targets, targeting insulin resistance, hepatic de novo lipogenesis, or substrate utilization; (2) inflam-matory pathways, inhibiting inflammatory cell recruitment/signaling, reduce oxidative/endoplasmic reticulum stress or are antiapoptotic; (3) the liver-gut axis, which modulates bile acid enterohepatic circulation/signaling or alters gut microbiota; and (4) antifibrotic targets, targeting hepatic stellate cells, decrease collagen deposition or increase fibrinolysis. IMPLICATIONS: Lifestyle modification must remain the cornerstone of treatment. Pharmacologic treatment is reserved for NASH or fibrosis, the presence of which requires histopathological confirmation. The disease complexity provides a strong rationale for combination therapies targeting multiple pathways simultaneously.

Mechanisms, screening modalities and treatment options for individuals with non-alcoholic fatty liver disease and type 2 diabetes.

Non-alcoholic fatty liver disease (NAFLD) exists as a spectrum of disease ranging from excessive accumulation of fat within the liver (simple steatosis), inflammation (non-alcoholic steatohepatitis) through to fibrosis, cirrhosis and end-stage liver disease. There is also an increased risk of hepatocellular carcinoma. The principal risk factor for NAFLD is overweight or obesity, along with type 2 diabetes, and NAFLD itself is also a risk factor for incident type 2 diabetes. Overweight/obesity is synergistic with alcohol consumption in causing progressive and insidious liver damage. Recent consensus advocates a change in nomenclature from NAFLD to 'metabolic associated fatty liver disease' (MAFLD), reflective of the associated metabolic abnormalities (insulin resistance/type 2 diabetes and metabolic syndrome components). Additional extra-hepatic manifestations of NAFLD include cardiovascular disease, chronic kidney disease and certain cancers. Unlike other micro- and macrovascular complications of type 2 diabetes, systematic screening or surveillance protocols have not been widely adopted in routine diabetes care to assess for presence/severity of NAFLD. Various screening tools are available (non-invasive tests and biochemical indices) combined with imaging techniques (e.g. transient elastography) to detect steatosis and more importantly advanced fibrosis/cirrhosis to facilitate appropriate surveillance. Liver biopsy may be sometimes necessary. Treatment options for type 2 diabetes, including lifestyle interventions (dietary change and physical activity), glucose-lowering therapies and metabolic surgery, can modulate hepatic steatosis and to a lesser extent fibrosis. Awareness of the impact of liver disease on the choice of glucose-lowering medications in individuals with type 2 diabetes is also critical.