Glossary

A B C D E F G H I J K L M N O P Q R S T U V W X Y Z #

A

Abstract
Summary of a study, which may be published alone or as an introduction to a full scientific paper.
Allocation concealment
The process used to prevent advance knowledge of group assignment in a randomised controlled trial (RCT). The allocation process should be impervious to any influence by the individual making the allocation, by being administered by someone who is not responsible for recruiting participants.
Amenorrhoea

The absence or cessation of menstruation.

Anovulatory

A menstrual cycle in which ovulation does not occur.

Anxiety
A feeling of apprehension, fear, nervousness or dread accompanied by restlessness or tension.
Applicability
How well the results of a study or NICE evidence review can answer a clinical question or be applied to the population being considered.
Arm (of a clinical study)
Subsection of individuals within a study who receive one particular intervention, for example placebo arm.
Association
Statistical relationship between 2 or more events, characteristics or other variables. The relationship may or may not be causal.
Asymptomatic
Causes no symptoms.
Attrition bias
Systematic differences between comparison groups for withdrawal or exclusion of participants from a study.
Available case analysis (ACA)
Analysis of data that is available for participants at the end of follow-up.

B

Baseline
The initial set of measurements at the beginning of a study (after run-in period where applicable) with which subsequent results are compared.
Before-and-after study
A study that investigates the effects of an intervention by measuring particular characteristics of a population both before and after taking the intervention, and assessing any change that occurs.
Bias
Influences on a study that can make the results look better or worse than they really are. Bias can occur by chance, deliberately or as a result of systematic errors in the design and execution of a study. It can also occur at different stages in the research process, for example during the collection, analysis, interpretation, publication or review of research data.
Bilateral oophorectomy
The surgical removal of both ovaries.
Bilateral salpingo oophorectom

Bilateral salpingo oophorectomy:

The surgical removal of both ovaries and fallopian tubes.

Biopsy
A minor surgical procedure during which a small tissue specimen is removed and examined microscopically for the presence of disease (often cancer).
Black cohosh
A herb, typically used in non-prescription supplement form.
Body mass index (BMI)
A number calculated from a person’s weight and height (kilograms/metres squared) that provides, for most people, a reliable indicator of body size.
Bone density or Bone mineral density (BMD)
The amount of mineralised tissue in a segment of bone. Measuring BMD is frequently used to evaluate bone strength and predict fracture risk. Results are reported as T-scores (comparison with the ideal BMD in healthy young adults) and Z-scores (comparison with other adults of the same age).
BRCA1 or BRCA2

The genes most commonly affected in hereditary breast and ovarian cancer.  

Breast cancer
A disease in which abnormal (malignant) cells in the breast divide and multiply in an uncontrolled fashion. The cells can invade nearby tissue and can spread through the bloodstream and lymphatic system (lymph nodes) to other parts of the body.

C

Cardiovascular disease (CVD)
An umbrella term used to describe many conditions related to the circulatory system, both inside and outside the heart. Includes heart disease, coronary artery disease (CAD) and coronary heart disease (CHD) as well as peripheral vascular disease.
Carer (caregiver)
Someone who looks after family, partners or friends in need of help because they are ill, frail or have a disability.
Case series
Report of a number of cases of a given disease, usually covering the course of the disease and the response to treatment. There is no comparison (control) group of patients.
Clinical effectiveness
How well a specific test or treatment works when used in the 'real world' (for example when used by a doctor with a patient at home), rather than in a carefully controlled clinical trial. Trials that assess clinical effectiveness are sometimes called management trials. Clinical effectiveness is not the same as efficacy.
Clinical efficacy
The extent to which an intervention is active when studied under controlled research conditions.
Clinician
A healthcare professional who provides patient care. For example a doctor, nurse or physiotherapist.
Cochrane Review
The Cochrane Library consists of a regularly updated collection of evidence-based medicine databases including the Cochrane Database of Systematic Reviews (reviews of RCTs prepared by the Cochrane Collaboration).
Cognitive function
Conscious intellectual activity (thinking, reasoning, remembering).
Cohort study
A study with 2 or more groups of people – cohorts – with similar characteristics. One group receives a treatment, is exposed to a risk factor or has a particular symptom and the other group does not. The study follows their progress over time and records what happens.
Comorbidity
A disease or condition that someone has in addition to the health problem being studied or treated.
Compounded bioidentical hormones (CBH)
Unregulated plant-derived hormonal combinations that are chemically similar or structurally identical to human hormones that are compounded by pharmacies to the specification of the prescriber.
Concealment of allocation
The process used to ensure that the person deciding to enter a participant into an RCT does not know the comparison group into which that individual will be allocated. This is distinct from blinding and is aimed at preventing selection bias. Some attempts at concealing allocation are more prone to manipulation than others and the method of allocation concealment is used as an assessment of the quality of a trial.
Confounding factor
Something that influences a study and can result in misleading findings if it is not understood or appropriately dealt with. For example, a study of heart disease may look at a group of people who exercise regularly and a group who do not exercise. If the ages of the people in the 2 groups are different, then any difference in heart disease rates between the 2 groups could be because of age rather than exercise. Therefore age is a confounding factor.
Continuous outcome
Data with a potentially infinite number of possible values within a given range. Height, weight and blood pressure are examples of continuous variables.
Continuously

The progestogen is taken daily throughout the cycle.

Contraception
Any method used to prevent pregnancy during sexual activity. Perimenopausal women who wish to avoid pregnancy are advised to use reliable contraception until 2 years have passed without a menstrual period if aged under 50, until 1 year if aged 50 or older, or until the age of 55 years. (See NICE Contraception clinical knowledge summary)
Coronary artery disease (CAD)
Sometimes called coronary heart disease (CHD). The most common form of cardiovascular disease, CAD refers to damaged or diseased blood vessels (coronary arteries) that supply blood to the heart muscle.
Cost-effectiveness analysis (CEA)
Cost-effectiveness analysis is one of the tools used to carry out an economic evaluation. The benefits are expressed in non-monetary terms related to health, such as symptom-free days, heart attacks avoided, deaths avoided or life years gained (that is, the number of years by which life is extended as a result of the intervention).
Cost-effectiveness model
An explicit mathematical framework which is used to represent clinical decision problems and incorporate evidence from a variety of sources in order to estimate the costs and health outcomes.
COX proportional hazard model
In survival analysis, a statistical model that asserts that the effect of the study factors (for example the intervention of interest) on the hazard rate (the risk of occurrence of an event) in the study population is multiplicative and does not change over time.
Credible interval (CrI)
The Bayesian equivalent of a confidence interval.

D

DCIS

Ductal carcinoma in situ.

DCIS is the presence of abnormal cells inside a milk duct in the breast. DCIS is considered the earliest form of breast cancer.

Decision analysis
An explicit quantitative approach to decision-making under uncertainty, based on evidence from research. This evidence is translated into probabilities, and then into diagrams or decision trees which direct the clinician through a succession of possible scenarios, actions and outcomes.
Depression
Altered mood characterised by severe despondency or despair, often with feelings of inadequacy or guilt, which is persistent and interferes with activities of daily living.
Diabetes
A group of diseases in which the body cannot properly control the amount of sugar in the blood, resulting in high sugar levels that may cause a variety of complications ranging from cardiovascular disease to blindness and kidney failure. Diabetes occurs when the body does not produce enough insulin or does not use it properly (insulin resistance).
Dichotomous outcomes
Outcome that can take one of 2 possible values, such as dead/alive, smoker/non-smoker, present/not present (also called binary data).
Discounting
Costs and perhaps benefits incurred today have a higher value than costs and benefits occurring in the future. Discounting health benefits reflects individual preference for benefits to be experienced in the present rather than the future. Discounting costs reflects individual preference for costs to be experienced in the future rather than the present.
Dominance
A health economics term. When comparing tests or treatments, an option that is both less effective and costs more is said to be 'dominated' by the alternative.
Drop-out
A participant who withdraws from a trial before the end.
Dyspareunia

Persistent or recurrent genital pain that occurs during or after intercourse.

E

Effect (as in effect measure, treatment effect, estimate of effect, effect size)
A measure that shows the magnitude of the outcome in 1 group compared with that in a control group. For example, if the absolute risk reduction is shown to be 5% and it is the outcome of interest, the effect size is 5%. The effect size is usually tested, using statistics, to find out how likely it is that the effect is a result of the treatment and has not just happened by chance.
Effectiveness
How beneficial a test or treatment is under usual or everyday conditions.
Efficacy
How beneficial a test, treatment or public health intervention is under ideal conditions (for example in a laboratory).
Endometrial cancer
Cancer of the inner lining (endometrium) of the uterus.
Endometrium

The lining of the womb

Epidemiological study
The study of a disease within a population, defining its incidence and prevalence and examining the roles of external influences (for example infection, diet) and interventions.
EQ-5D (EuroQol 5 dimensions)
A standardised instrument used to measure health-related quality of life. It provides a single index value for health status.
Equivalence study
A trial designed to determine whether the response to 2 or more treatments differs by an amount that is clinically unimportant. This is usually demonstrated by showing that the true treatment difference is likely to lie between a lower and an upper equivalence level of clinically acceptable differences.
Estradiol
Also called 17beta-estradiol. The most potent of the naturally occurring oestrogens and the primary oestrogen produced by women in their reproductive years. Available in oral, skin patch and vaginal prescription drugs.
Evidence
Information on which a decision or guidance is based. Evidence is obtained from a range of sources including RCTs, observational studies, expert opinion (of clinical professionals or patients).
Exclusion criteria (clinical study)
Criteria that define who is not eligible to participate in a clinical study.
Exclusion criteria (literature review)
Explicit standards used to decide which studies should be excluded from consideration as potential sources of evidence.
Extended dominance
If Option A is both more clinically effective than Option B and has a lower cost per unit of effect when both are compared with a do-nothing alternative, then Option A is said to have extended dominance over Option B. Option A is therefore more cost effective and should be preferred, other things remaining equal.
Extensive endometriosis

Endometriosis that is not confined to the uterus.

Extrapolation
An assumption that the results of studies of a specific population will also hold true for another population with similar characteristics.

F

False negative
A diagnostic test result that incorrectly indicates that an individual does not have the disease of interest, when they do actually have it.
False positive
A diagnostic test result that incorrectly indicates that an individual has the disease of interest, when they actually do not have it.
Fertile
Capable of reproducing.
Fixed-effect model
In meta-analysis, a model that calculates a pooled effect estimate using the assumption that all observed variation between studies is caused by random sample variability. Studies are assumed to estimating the same overall effect.
Follicle-stimulating hormone (FSH)
A hormone produced by the pituitary gland (located at the base of the brain). In women, FSH stimulates the growth of ovarian follicles (the small cysts that hold the eggs) and the supporting cells responsible for the growth and nurturing of the egg. FSH also stimulates production of oestrogen by the ovaries. When oestrogen production is low (for example after menopause), FSH levels will be high.
Follow-up
Observation over a period of time of an individual, group or initially defined population whose appropriate characteristics have been assessed in order to observe changes in health status or health-related variables.
Fracture
The breaking of bone, resulting either from trauma (such as a fall) or because bone has become weakened from a condition such as osteoporosis.
Fragility fracture
Fractures that result from mechanical forces that would not ordinarily result in fracture (such as a fall from a standing height or less). Reduced bone density is a major risk factor for fragility fractures, which occur most commonly in the spine, hip and wrist.

G

Generalisability
The extent to which the results of a study hold true for groups that did not participate in the research.
Genitourinary syndrome of meno

Genitourinary syndrome of menopause: describes combined vulvovaginal and urinary tract symptoms caused by thinning and shrinking of the tissues of the vulva, vagina, urethra, and bladder due to oestrogen deficiency. (NICE CKS)

Glossary

A glossary is a collection of words pertaining to a specific topic. In your articles or dissertation, it’s a list of all terms you used that may not immediately be obvious to your reader. Your glossary only needs to include terms that your reader may not be familiar with, and it’s intended to enhance their understanding of your work. Glossaries are not mandatory, but if you use a lot of technical or field-specific terms, it may improve readability to add one.

Gold standard
A method, procedure or measurement that is widely accepted as being the best available to test for or treat a disease.
Gonadotrophins

Hormones released from the brain that regulate ovarian function.

GRADE, GRADE profile
A system developed by the GRADE Working Group to address the short-comings of present grading systems in healthcare. The GRADE system uses a common, sensible and transparent approach to grading the quality of evidence. The results of applying the GRADE system to clinical trial data are displayed in a table known as a GRADE profile.
GSM

GSM: abbreviation for genitourinary syndrome of menopause. This was previously known as vulvovaginal atrophy or urogenital atrophy. (NICE CKS)

H

Harms
Adverse effects of an intervention.
Hazard ratio
A hazard is the rate at which events happen, so that the probability of an event happening in a short time interval is the length of time multiplied by the hazard. Although the hazard may vary with time, the assumption in proportional hazard models for survival analysis is that the hazard in one group is a constant proportion of the hazard in the other group. This proportion is the hazard ratio. .
Health economics
Study or analysis of the cost of using and distributing healthcare resources.
Health-related quality of life (HRQoL)
A measure of the effects of an illness to see how it affects someone's day-to-day life.
Heterogeneity
The term is used in meta-analyses and systematic reviews to describe when the results of a test or treatment (or estimates of its effect) differ.
Hormone replacement therapy (HRT)
Prescription drugs used most often when treating menopause symptoms. Encompasses both oestrogen therapy and oestrogen plus progestogen therapy.
Hot flush
The most common menopause-related symptom, comprising a sudden feeling of heat, resulting in a red, flushed face and neck, perspiration and a rapid heartbeat, lasting a short time and often followed by a cold chill.
HSDD

Hypoactive Sexual Desire Disorder - Symptoms of HSDD include decreased spontaneous sexual thoughts, decreased responsiveness to stimulation...

Hypertension
Abnormally high blood pressure.
Hysterectomy
Surgical removal of the uterus. This does not necessarily involve removal of the ovaries (see Bilateral oophorectomy).

I

Iatrogenic
Adverse consequence of medical examination treatment or advice, for example early menopause occurring after surgical removal of the ovaries.
Idiopathic

A condition for which the cause is unknown.

Imprecision
Results are imprecise when studies include relatively few patients and few events and thus have wide confidence intervals around the estimate of effect.
Incidence
The incidence of a disease is the rate at which new cases occur in a population during a specified period.
Inclusion criteria (clinical study)
Specific criteria that define who is eligible to participate in a clinical study.
Inclusion criteria (literature review)
Explicit criteria used to decide which studies should be considered as potential sources of evidence.
Incremental cost
The extra cost linked to using one test or treatment rather than another. Or the additional cost of doing a test or providing a treatment more frequently.
Incremental cost effectiveness ratio (ICER)
The difference in the mean costs in the population of interest divided by the differences in the mean outcomes in the population of interest for one treatment compared with another.
Incremental net benefit (INB)
The value (usually in monetary terms) of an intervention net of its cost compared with a comparator intervention. The INB can be calculated for a given cost-effectiveness (willingness to pay) threshold. If the threshold is £20,000 per QALY gained then the INB is calculated as: (£20,000×QALYs gained) minus incremental cost.
Indirectness
The available evidence is different to the review question being addressed, in terms of population, intervention, comparison and outcome (PICO).
Induced menopause.
Menopause brought on by treatment, for example surgical removal of the ovaries.
Intervention
In medical terms this could be a drug treatment, surgical procedure, diagnostic or psychological therapy. Examples of public health interventions could include action to help someone to be physically active or to eat a more healthy diet.
Isoflavones
Naturally occurring oestrogen-like compounds found in soybeans, soy products and red clover.

K

Kappa statistic
A statistical measure of inter-rater agreement that takes into account the agreement occurring by chance
Knowledge Base

A knowledge base is a self-serve online library of information about a product, service, department, or topic. The data in your knowledge base can come from anywhere. Typically, contributors who are well versed in the relevant subjects add to and expand the knowledge base. The content can range from the ins and outs of your HR or legal department to an explanation of how a product works. 

L

Latrogenic

A condition caused by medical treatment.

Length of stay
The total number of days a patient stays in hospital.
Licence
See Product licence.
Life years gained
Mean average years of life gained per person as a result of the intervention compared with an alternative intervention.
Likelihood ratio
The likelihood ratio combines information about the sensitivity and specificity. It tells you how much a positive or negative result changes the likelihood that a patient would have the disease. The likelihood ratio of a positive test result (LR+) is sensitivity divided by (1 minus specificity).
LNG IUS

LNG-IUS: An intrauterine coil that releases the progestogen Levonorgestrel. Examples include the Mirena coil or Levosert.

Loss to follow-up
Patients who have withdrawn from the clinical trial at the point of follow-up.
Low mood
Mild depression symptoms that impair quality of life but are usually intermittent and often associated with hormonal fluctuations, for example in the perimenopause.
Luteal phase

The time between ovulation and the next period in the menstrual cycle.

M

Mammogram
Specialised X-rays of the breast used to detect abnormal growths or changes in the breast tissue
Markov model
A method for estimating long-term costs and effects for recurrent or chronic conditions, based on health states and the probability of transition between them within a given time period (cycle).
Mean
An average value, calculated by adding all the observations and dividing by the number of observations.
Mean difference
In meta-analysis, a method used to combine measures on continuous scales (such as weight), where the mean, standard deviation and sample size in each group are known. The weight given to the difference in means from each study (for example how much influence each study has on the overall results of the meta-analysis) is determined by the precision of its estimate of effect.
Median
The value of the observation that comes half-way when the observations are ranked in order.
Menopausal women
This includes women in perimenopause and postmenopause.
Menopause
A biological stage in a woman's life that occurs when she stops menstruating and reaches the end of her natural reproductive life. Usually it is defined as having occurred when a woman has not had a period for 12 consecutive months (for women reaching menopause naturally). The changes associated with menopause occur when the ovaries stop maturing eggs and secreting oestrogen and progesterone.
Menstrual cycle
The cycle of changes in the uterus and ovaries during a woman’s reproductive life, resulting in menstruation, typically every 4 weeks. During the cycle an egg develops in the ovary and is released, the lining of the uterus thickens to prepare for implantation of a fertilised egg, and if this does not occur, the lining of the uterus is shed through menstruation and the cycle begins again. This cycle typically becomes irregular during perimenopause and ends completely at menopause.
Meta-analysis
A method often used in systematic reviews. Results from several studies of the same test or treatment are combined to estimate the overall effect of the treatment.
Minimal important difference (MID)
Threshold for clinical importance which represents the minimal important difference for benefit or for harm; for example the threshold at which drug A is less effective than drug B by an amount that is clinically important to patients.
Monte Carlo
A technique used to approximate the probability of certain outcomes by running multiple simulations using random variables.
Multivariate model
A statistical model for analysis of the relationship between 2 or more predictors, (independent) variables and the outcome (dependent) variable.

N

Net monetary benefit (NMB)
The value (usually in monetary terms) of an intervention net of its cost. The NMB can be calculated for a given cost-effectiveness (willingness to pay) threshold. If the threshold is £20,000 per QALY gained then the NMB is calculated as: (£20,000×QALYs gained) minus cost.
Network meta-analysis
Meta-analysis in which multiple treatments (that is, 3 or more) are being compared using both direct comparisons of interventions within RCTs and indirect comparisons across trials based on a common comparator.
Night sweats
Hot flushes that occur at night causing heavy perspiration, often interfering with sleep.
Non-inferiority trial
A trial designed to determine whether the effect of a new treatment is not worse than a standard treatment by more than a pre-specified amount. A one-sided version of an equivalence trial.
Number needed to treat (NNT)
The average number of patients who need to be treated to get a positive outcome. For example, if the NNT is 4, then 4 patients would have to be treated to ensure 1 of them gets better. The closer the NNT is to 1, the better the treatment. For example, if you give a stroke prevention drug to 20 people before 1 stroke is prevented, the number needed to treat is 20.

O

Obesity
Excessive accumulation of fat in the body. Obesity is defined as a body mass index over 30 kg/m2 (World Health Organization) and is associated with health problems including Type 2 diabetes, cardiovascular disease, stroke, hypertension, some cancers and premature death.
Observational study
Individuals or groups are observed or certain factors are measured. No attempt is made to affect the outcome. For example, an observational study of a disease or treatment would allow 'nature' or usual medical care to take its course. Changes or differences in one characteristic (for example whether or not people received a specific treatment or intervention) are studied without intervening. There is a greater risk of selection bias than in experimental studies.
Oestrogen plus progestogen therapy
Also known as combination hormone therapy. Oestrogen is the hormone in this duo that provides the most relief for menopause-related symptoms. Progestogen is added to protect the lining of the uterus from oestrogen stimulation which increases risk of endometrial cancer if given alone.
Oestrogens
Hormonal compounds produced by the ovaries, which influence the growth and health of female reproductive organs and are active in many body tissues. The 3 main naturally occurring oestrogens in women are oestradiol (premenopausal women), oestrone and estriol. Oestradiol levels fall after menopause. Several types of oestrogen therapies are available for treatment of menopause; they are also in the combined oral contraceptive but at higher doses than those used for menopause treatment.
Oligomenorrhea

Oligomenorrhoea is infrequent menstruation defined by a cycle length between 6 weeks and 6 months.

More detail: https://gpnotebook.com/simplepage.cfm?ID=-1670709237

Oocytes

A developing egg in the ovary.

Opportunity cost
The loss of other healthcare programmes displaced by investment in or introduction of another intervention. This may be best measured by the health benefits that could have been achieved had the money been spent on the next best alternative healthcare intervention.
Osteoporosis
A condition in which the bone density of the skeleton has decreased to a point where bone has become fragile and at higher risk for fractures, often with little or no trauma. Common among older women, because bone mineral loss usually occurs after menopause, which is related to the decline in estrogen levels.

P

Performance bias
Systematic differences between intervention groups in care provided apart from the intervention being evaluated. Blinding of study participants (both the recipients and providers of care) is used to protect against performance bias.
Perimenopause.
The time in which a woman has irregular cycles of ovulation and menstruation leading up to menopause and continuing until 12 months after her final period. The perimenopause is also known as the menopausal transition or climacteric.
Phytoestrogens
Plant compounds (such as isoflavones) that have a chemical structure similar to that of oestrogen and have weak oestrogen-like biologic activity. Available in foods (such as soy) and as non-prescription supplements.
Placebo
A fake (or dummy) treatment given to participants in the control group of a clinical trial. It is indistinguishable from the actual treatment (which is given to participants in the experimental group). The aim is to determine what effect the experimental treatment has had over and above any placebo effect caused because someone has received (or thinks they have received) care or attention.
Placebo effect
A beneficial (or adverse) effect produced by a placebo and not due to any property of the placebo itself.
Post-hoc analysis
Statistical analyses that are not specified in the trial protocol and are generally suggested by the data.
Postmenopause
The time after menopause has occurred, starting when a woman has not had a period for 12 consecutive months.
Power (statistical)
The ability to demonstrate an association when one exists. Power is related to sample size; the larger the sample size, the greater the power and the lower the risk that a possible association could be missed.
Premature ovarian insufficiency
Menopause occurring before age 40 years (also known as premature ovarian failure or premature menopause). It can occur naturally or iatrogenically (that is, as a result of treatment).
Premenopause
The span of time from puberty (onset of menstrual periods) to perimenopause.
Prevalence
The prevalence of a disease is the proportion of a population that are cases at a point in time.
Primary care
Healthcare delivered outside hospitals. It includes a range of services provided by GPs, nurses, health visitors, midwives and other healthcare professionals and allied health professionals such as dentists, pharmacists and opticians.
Primary outcome
The outcome of greatest importance, usually the one in a study that the power calculation is based on.
Product licence
An authorisation from the Medicines and Healthcare Products Regulatory Agency (MHRA) to market a medicinal product.
Progestagen
A synthetic hormone virtually identical to progesterone, with similar biological effects. Several different progestogens exist and are used in hormone replacement therapy.
Progesterone
A naturally occurring hormone produced by the ovaries which acts on the lining of the uterus.
Prognosis
A probable course or outcome of a disease. Prognostic factors are patient or disease characteristics that influence the course. Good prognosis is associated with low rate of undesirable outcomes; poor prognosis is associated with a high rate of undesirable outcomes.
Prospective study
A research study in which the health or other characteristic of participants is monitored (or 'followed up') for a period of time, with events recorded as they happen. This contrasts with retrospective studies.
Protocol (review)
A document written prior to commencing a review that details exactly how evidence to answer a review question will be obtained and synthesised. It defines in detail the population of interest, the interventions, the comparators/controls and the outcomes of interest (PICO).
Publication bias
Publication bias occurs when researchers publish the results of studies showing that a treatment works well and don't publish those showing it did not have any effect. If this happens, analysis of the published results will not give an accurate idea of how well the treatment works. This type of bias can be assessed by a funnel plot.

Q

Quality of life
See Health-related quality of life.

R

Random effect model
In meta-analysis, a model that calculates a pooled effect estimate using the assumption that each study is estimating a different true treatment effect due to real differences between studies. Observed variation in effects are therefore caused by a combination of random sample variability (within-study variation) and heterogeneity between studies (between-study variation). The overall effects is an average of the estimated true study effects.
Randomisation
Assigning participants in a research study to different groups without taking any similarities or differences between them into account. For example, it could involve using a random numbers table or a computer-generated random sequence. It means that each individual (or each group in the case of cluster randomisation) has the same chance of receiving each intervention.
RCTs

Randomised controlled trials.

Red clover
A member of the legume plant family rich in phytoestrogens.
Reference standard
The test that is considered to be the best available method to establish the presence or absence of the outcome – this may not be the one that is routinely used in practice.
Reporting bias
See Publication bias.
Resource implication
The likely impact in terms of finance, workforce or other NHS resources.
Retrospective study
A research study that focuses on the past and present. The study examines past exposure to suspected risk factors for the disease or condition. Unlike prospective studies, it does not cover events that occur after the study group is selected.
Review question
The plan or set of steps to be followed in a study. A protocol for a systematic review describes the rationale for the review, the objectives and the methods that will be used to locate, select and critically appraise studies, and to collect and analyse data from the included studies.

S

Secondary care
Care provided in hospitals.
Secondary outcome
An outcome used to evaluate additional effects of the intervention deemed a priori as being less important than the primary outcomes.
Selection bias
Selection bias occurs if: · The characteristics of the people selected for a study differ from the wider population from which they have been drawn; or · There are differences between groups of participants in a study in terms of how likely they are to get better.
Selective estrogen-receptor modulator (SERM)
A compound that has a similar chemical structure to oestrogen and has an oestrogen-like effect on some tissues and an anti-oestrogen effect on others.
Sequentially

The progestogen is taken for 12-14 days in each cycle. This usually results in monthly withdrawal bleeds.

Sex steroids
Hormones such as oestrogen, progesterone and testosterone which are produced by the ovaries in women, testes in men or adrenal gland (in both women and men) that affect the function of the reproductive organs or development of sexual characteristics. Can also be used as medications either in naturally-occurring or synthesised form.
Significance (statistical)
A result is deemed statistically significant if the probability of the result occurring by chance is less than 1 in 20 (p<0.05).
Specificity
The proportion of true negatives that are correctly identified as such. For example, in diagnostic testing the specificity is the proportion of non-cases correctly diagnosed as non-cases. In terms of literature searching a highly specific search is generally narrow and aimed at picking up the key papers in a field and avoiding a wide range of papers.
St Johns wort

A perennial plant typically used in non-prescription supplement form by some women to ease mild to moderate depression.

Standard deviation (SD)
A measure of the spread or dispersion of a set of observations, calculated as the average difference from the mean value in the sample.
Subgroup analysis
An analysis in which the intervention effect is evaluated in a defined subset of the decision analysis or economic evaluation.

T

Treatment allocation
Assigning a participant to a particular arm of a trial.
True negative
A diagnostic test result that correctly indicates that an individual does not have the disease of interest when they actually do not have it.
True positive
A diagnostic test result that correctly indicates that an individual has the disease of interest when they do actually have it.

U

Univariate
Analysis which separately explores each variable in a data set.
Uterus
A small, hollow, pear-shaped organ in a woman's pelvis where menstrual bleeding originates and in which pregnancy develops, also called the womb.
Utility
In health economics, a utility is the measure of the preference or value that an individual or society places upon a particular health state. It is generally a number between 0 (representing death) and 1 (perfect health). The most widely used measure of benefit in cost-utility analysis is the quality-adjusted life year, but other measures include disability-adjusted life years (DALYs) and healthy year equivalents (HYEs).

V

Vagina
The tube that joins the lower part of the uterus to the outside of the body. Also known as the birth canal.
Vaginal dryness
Inadequate lubrication of the vagina, often caused by low oestrogen levels.
Vaginal/urogenital atrophy
Thinning and shrinking of the tissues of the vulva, vagina, urethra and bladder caused by lack of oestrogen that results in multiple symptoms such as vaginal dryness, vaginal irritation, a frequent need to urinate and urinary tract infections. Also referred to as genitourinary syndrome of menopause.
Vasomotor symptoms
Menopausal symptoms such as hot flushes and night sweats caused by constriction and dilation of blood vessels in the skin that can lead to a sudden increase in blood flow to allow heat loss.
Vitamin D
A nutrient that enables the body to absorb calcium, among other things. It is normally produced within the skin in response to sunlight and absorbed from dietary sources. Also available in supplement form.
VVA

Vulvovaginal Atrophy - Common symptoms include vaginal dryness, irritation, postcoital bleeding, and soreness.