adjusted odds ratio (aOR)—an odds ratio that controls for confounding variables.
Ashworth scale—a clinical measure of muscle spasticity based on an assessment of a patient’s muscle tone in different muscle groups.
association—the statistical relation between two or more events, characteristics, or other variables.
cannabis use disorder (CUD)—according to the Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition, a problem-causing pattern of cannabis use leading to clinically significant impairment or distress, as manifested by at least two distinguishing symptoms (e.g., cannabis is taken in larger amounts or for longer periods than intended; experience of craving; continued cannabis use despite the experience of physical, social, or interpersonal problems caused by cannabis use) occurring within a 12-month period.
case series—an analysis of a series of people with the disease (there is no comparison group in case series). Case series studies provide weaker evidence than case-control studies.
case-control study—an observational analytic study that enrolls one group of persons with a certain disease, chronic condition, or type of injury (case-patients) and a group of persons without the health problem (control subjects) and compares differences in exposures, behaviors, and other characteristics to identify and quantify associations, test hypotheses, and identify causes.
cohort study—an observational analytic study in which enrollment is based on one’s status of exposure to a certain factor or membership in a certain group. Populations are followed, and disease, death, or other health-related outcomes are documented and compared. Cohort studies can be either prospective or retrospective.
comparator—the agent to which the experimental arm of a study is compared (e.g., placebo, usual care, active control).
control—comparator against which the study treatment is evaluated (e.g., concurrent [placebo, no treatment, dose–response, active], and external [historical, published literature]).
cross-sectional study—a study in which a sample of persons from a population are enrolled and their exposures and health outcomes are measured simultaneously; a survey.
cultivar—a plant variety that has been produced in cultivation by selective breeding.
dose—the quantity of a drug that is used at one time or in fractional amounts during a given period of time.
evidence—information on which a conclusion about a cause-effect relationship is based. The most direct evidence for health effects in humans is usually based on studies of health endpoints that are conducted in humans, including randomized trials and nonrandomized epidemiologic studies. Additional evidence can be provided by studies of intermediate endpoints or markers in humans as well as by nonhuman studies. The committee has developed a strength-of-evidence table so that the level of evidence is expressed in uniform terms and calibrated throughout the report.
exclusion criteria—a list of characteristics in a protocol, any one of which may exclude a potential subject from participation in a study.
incidence—the number of new cases of a condition, symptom, death, or injury that develop during a specified period of time.
inclusion criteria—the criteria in a protocol that prospective subjects must meet to be eligible for participation in a study.
meta-analysis—a statistical technique for combining (pooling) the results of a number of studies that address the same question and report on the same outcomes to produce a more precise summary estimate of the effect on a particular outcome. Meta-analyses are frequently used in systematic reviews.
mortality—death or loss of life.
narrative review—narrative reviews tend to be mainly descriptive, do not involve a systematic search of the literature, and thereby often focus on a subset of studies in an area chosen based on availability or author selection. Generally, narrative reviews offer lower-quality evidence than systematic reviews. For this reason, and for the purpose of the report, narrative reviews are classified as primary literature.
observational study—a study in which the investigator observes rather than influences exposure and disease among participants. Case-control and cohort studies are examples of observational studies.
odds ratio (OR)—one measure of treatment effectiveness. It is the odds of an event happening in the experimental group expressed as a proportion of the odds of an event happening in the control group. The closer the OR is to 1, the smaller the difference in effect is between the experimental intervention and the control intervention. If the OR is greater (or less) than 1, then the effects of the treatment are more (or less) than those of the control treatment. Note that the effects being measured may be adverse (e.g., death or disability) or desirable (e.g., survival). When events are rare, the OR is analogous to the relative risk (RR), but as event rates increase, the OR and RR diverge.
outcome—events or experiences that clinicians or investigators examining the impact of an intervention or exposure measure because they believe such events or experiences may be influenced by the intervention or exposure.
pooled estimate—an average derived from multiple studies with varying data but with a common measurement. Typically found in systematic reviews and meta-analyses.
potency—the amount of drug required to produce a specific level of effect.
preclinical—research studies that use cell culture or animal models to test scientific hypotheses. These studies are performed prior to clinical studies that use human subjects.
prevalence—the number or proportion of individuals within a given population who share a specific characteristic.
primary literature—peer-reviewed accounts of original research that contribute new evidence to science. By comparison, systematic reviews and literature reviews analyze existing evidence. Examples of the types of primary literature used in the report are randomized controlled trials, cohort studies, cross-sectional studies, case-control studies, and case series.
problem cannabis use—a symptom of cannabis use disorder. Problem cannabis use includes the experience of persistent or recurrent social, interpersonal, occupational, academic, recreational, psychological, or physical problems caused or exacerbated by cannabis use.
randomized controlled trial (RCT)—a trial in which participants are randomly assigned to one of two or more groups, at least one of which (the experimental group) receives an intervention that is being tested and another (the comparison or control group) receives an alternative treatment or placebo. This design allows assessment of the relative effects of interventions.
relative risk (RR)—a ratio of the risk of an event among an exposed population to the risk among the unexposed.
route of administration—the path by which a drug is taken into the body.
systematic review—research that summarizes the evidence on a clearly formulated question according to a predefined protocol. Systematic and explicit methods to identify, select, and appraise relevant studies and to extract, collate, and report their findings are used. Statistical meta-analysis may or may not be used. Systematic reviews were the optimal data source for identifying associations between cannabis exposure and all of the health endpoints discussed in this report.