pl. indices [L. index, stem indic-, pointer]

1. The forefinger.
2. The ratio of the measurement of a given substance to that of a fixed standard.

index of activities of daily living

A tool that assesses six basic human functions: bathing, dressing, toileting, transfer, continence, and feeding. The index provides an objective method of assessing self-maintenance among diverse groups of people, e.g., older adults and those with chronic illnesses, disabilities, and impairments, and of describing their health needs and outcomes.

addiction severity index

A structured assessment tool that evaluates the impact of addictive behavior on seven areas of living: alcohol use, drug use, employment, family relationships, illegal activities, physical health, and psychological health.

alveolar index

SEE: Gnathic index.

ankle-brachial index

ABBR: ABI A measure of the adequacy of blood flow to the arteries of the legs. It is used to gauge the severity of peripheral vascular disease.

The index is obtained by measuring the systolic blood pressure in the upper and lower extremities after the patient has been lying on his or her back for about 5 min and then repeating the measurements after the patient walks for 5 min. There are several ways to obtain an ABI. The most accurate test results are obtained by measuring the blood pressure in both arms using a blood pressure cuff and Doppler ultrasound and recording the higher of these two pressures. The measurement is repeated in each leg, with measurement of blood pressures at both the posterior tibial and dorsalis pedis arteries. The pressure that should be recorded is the pressure found during the first return of a pulse to the cuffed limb. The blood pressure in each leg is divided by the blood pressure in the higher pressure of the two arms to obtain an ABI for each lower extremity. An ABI above 0.9 is normal, except when it exceeds 1.3 (an indicator of severe peripheral arterial obstruction). Severe obstruction is also indicated by an ABI of less than 0.5. Moderate peripheral arterial disease is suggested by an ABI of 0.8. A drop in the ABI after exercise also strongly suggests peripheral arterial disease. Patients with mild or moderately abnormal ABIs are usually treated with antiplatelet medications, an exercise regimen, and cholesterol-lowering drugs or diet. Those who smoke are encouraged to quit. Patients with severe disease may need angiography and, in some instances, arterial bypass surgery or stenting.
Ankle blood pressure measurement Measurement of blood pressures at the ankles.

apnea-hypopnea index

ABBR: AHI The number of times in an hour when a sleeping person either stops breathing completely or has limited airflow. Each episode must last at least 10 sec. Although AHI is an imperfect diagnostic tool, it is used as an indicator of obstructive sleep apnea. An AHI of 30 or more events in an hour indicates severe sleep apnea; 15 to 29 events suggests moderate apnea; and 5 to 14 events indicates mild apnea.

arousal index

ABBR: ArI The number of times an hour that a person wakes up from sleep because of apnea, hypopnea, periodic limb movements, or other cause.

Barthel index

SEE: Barthel index

bispectral index

ABBR: BIS An electroencephalographic measure of the effect of sedative and hypnotic drugs on an anesthetized patient. It is used (along with clinical assessment of the patient) to determine the level of central nervous system depression. The index ranges from zero (completely unresponsive to stimulation) to 100 (awake and alert). At levels below 60, most patients are adequately sedated for surgery.

body mass index

ABBR: BMI An index for estimating obesity. The BMI can be obtained by dividing weight in kilograms by height in meters squared, or according to the following formula: BMI = (Weight/2.205) / (Height/39.37)2. In adults, a BMI greater than 30 kg/m2 indicates obesity; a BMI greater than 40 kg/m2 indicates morbid obesity; and a BMI less than 18.5 kg/m2 indicates a person is underweight.
SYN: SEE: Quetelet index

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body mass index adjusted for age

The weight of a child between 2 and 19 years compared to other children of the same gender and height. It provides an estimate of nutritional adequacy or obesity.

burn scar index

A rating scale developed to assess hypertrophic burn scars and their rate of development or resolution. It is available at
SYN: SEE: Vancouver scar index;; SEE: Vancouver scar scale

cardiac index

The cardiac output (expressed in liters per minute) divided by the body surface area (expressed in square meters).

cephalic index

The biparietal diameter of the skull divided by its occipitofrontal diameter, all multiplied by 100.

cerebral index

The ratio of greatest transverse diameter to the greatest anteroposterior diameter of the cranium.

chemotherapeutic index

The ratio of the toxicity of a drug, expressed as the maximum tolerated dose per kilogram of body weight to the minimal curative dose per kilogram of body weight. This index is used in judging the safety and effectiveness of drugs.

clinical risk index for babies

ABBR: CRIB An index of the severity of illness, used to estimate the likelihood of mortality in very low birth weight infants who are cared for in a neonatal intensive care unit.

color index

An outmoded method of expressing the amount of hemoglobin present in each red cell.

CT dose index

A measure of the radiation dose delivered to tissue during a computed tomography (CT) scan, consisting of the radiation delivered to tissues in the center and the periphery of the scan, and adjusted for the pitch of the beam.

Cumulative Index to Nursing and Allied Health Literature

SEE: Cumulative Index to Nursing and Allied Health Literature

delta neutrophil index

ABBR: DNI The measured difference between white blood cells with excessive myeloperoxidase levels and granulocytes with excessive lobulation. When the DNI exceeds 40%, the patient may be septic.

dental index

A system of numbers for indicating comparative size of the teeth.

DMF index

The index of dental health and caries experience based on the number of decayed, missing, and filled (DMF) teeth or tooth surfaces.

dynamic gait index

ABBR: DGI A tool for evaluating a patient's ability to modify gait by changing task demands, esp. in patients with dizziness and balance deficits. This test is used to identify patients, esp. older adults, who are predisposed to falling. Patients are graded on their ability to vary speed, turn their heads, turn their bodies, step over and around obstacles, climb stairs, turn while walking, pick objects up from the floor, and perform alternate step-ups on a stool.

exposure index

A relative value indicating the quantity of ionizing radiation received by a digital radiographic image receptor. Although vendors currently use many kinds of exposure indices, e.g., Sensitivity Numbers, standardization is being developed by physicists' organizations.

fatigue index

The difference between the muscle power generated during peak exertion and the power that can be generated after repeated loading and unloading of the muscle.

Frenchay Activities Index

A formal interview for patients who have suffered a stroke to compare their functional abilities preceding and following the stroke. The patient describes how employment, meal preparation and clean up, gardening, shopping, and other activities of daily living have been altered by the stroke.

gas exchange index

Any of several measurements of the efficiency of respiration, esp. of the extent of intrapulmonary shunting in respiratory failure. One commonly used gas exchange index is the alveolar-arterial oxygen tension difference, which is a measurement derived from an analysis of the oxygen tension of an arterial blood gas compared with the atmospheric oxygen content.

glycemic index

An index for measuring the ability of a food to increase blood glucose levels as compared with consumption of either glucose or white bread as the standard. Foods with a low glycemic index result in a slower rise and lower maximum elevation of blood glucose levels than foods with a higher glycemic index. Consumption of low glycemic index foods can contribute to blood glucose regulation in patients with diabetes mellitus. A second use for the index is to identify the choice of food that will raise blood sugar levels after, say, endurance exercise.

gnathic index

A measure of the degree of projection of the upper jaw by finding the ratio of the distance from the nasion to the basion to that of the basion to the alveolar point and then multiplying by 100.
SYN: SEE: alveolar index

HCI index

The relative intensity or acuity of a hospitalization. The index is derived from the time spent in a hospital and the number of times a physician visited the patient each day. The variables are adjusted for the patient's age, gender, history of illness, and race.

human development index

A measure of national quality of life used by the United Nations Development Program. It consists of three elements: life expectancy at birth, mean years and expected years of schooling, and the gross national income at purchasing power parity per capita.

Insall-Salvati index

SEE: Insall-Salvati index

International Sensitivity Index

ABBR: ISI A laboratory standard for thromboplastins, the reagents used to determine the prothrombin time (PT). Because thromboplastin contents vary, PT results performed on the same sample of blood in different laboratories can be markedly different, even though the patient's actual level of anticoagulation is a constant. The ISI is used to calculate the international normalized ratio, a standardized measure of anticoagulation, thus enabling health care professionals working with different laboratories to compare results and adjust anticoagulant doses according to a single set of guidelines.

Karnofsky Index

SEE: Karnofsky Index

kidney donor profile index

An assessment tool for estimating the potential viability of a donated kidney after implantation into a recipient.

labeling index

1. The rate at which cells take up identifiable chemicals used in cell division.
2. A measure of the rate of the reproduction of cells, as in fetal tissue development or the growth of cancers.

left ventricular mass index

ABBR: LVMI A measure of left ventricular hypertrophy obtained by determining the mass of the myocardium with echocardiography, and adjusting it for the height of the patient.

leukopenic index

A test formerly used to determine hypersensitivity to foods, in which the white blood cell count is checked 90 min after the consumption of a suspected allergen. A precipitous decrease in the white blood cell count within 90 min after ingestion of the test food was thought to indicate that the food was incompatible with that person.

life satisfaction index

ABBR: LSI A self-reporting instrument to measure personal fulfillment or contentment, esp. with one's social relationships, occupation, maturation, or aging. A total of five rating scales are used.

McMurtry index

SEE: McMurtry index

Matsuda index

SEE: Matsuda index

Index Medicus

A publication of the National Library of Medicine that lists biomedical and health sciences journal articles by title, subject, field, and country of publication. The major national and international medical and biological journals are indexed.

Mentzer Index

SEE: Mentzer index

mitotic index

The number of mitoses seen in a biopsy specimen per square millimeter of tissue examined. Mitoses in tissue are indicative of malignancy. The higher the mitotic index, the more rapidly a tumor is dividing and the worse the prognosis.

nasal index

The greatest width of the nasal aperture in relation to a line from the lower edge of the nasal aperture to the nasion.

notch width index

The width of the femoral intercondylar notch divided by the width of the femoral condyles.

opsonic index

A ratio of the number of bacteria that are ingested by leukocytes contained in the serum of a normal individual compared with the number ingested by leukocytes in the study patient's blood serum.

oral hygiene index

ABBR: OHI A popular indicator to determine oral hygiene status in epidemiological studies. The index consists of an oral debris score and a calculus score. Six indicator teeth are examined for soft deposits and calculus. Numerical values are assigned to the six indicator teeth according to the extraneous deposits present. The scores are added and divided by the number of surfaces examined to calculate the average oral hygiene score.
SEE: Periodontal (Ramfjord) Index

Oswestry Disability Index

ABBR: ODI A questionnaire that requires a patient to rate the effect of back pain on 10 different activities, each having six levels of disability. The test was designed to assess patients with failed back surgery, but it is widely used for nonsurgical patients with other spinal conditions.
SYN: SEE: Oswestry disability score

oxygen desaturation index

ABBR: ODI In sleep-disordered breathing, the number of times an hour that a person’s oxygenation falls by more than 4% from a baseline.

oxygenation index

ABBR: OI A measure of the efficiency of oxygen exchange by the lungs. The index is used in critical care medicine to assess the severity of acute lung injury and to gauge the effectiveness of ventilator management strategies. Mathematically, it is represented as the product of the fractional concentration of inspired oxygen and the mean airway pressure, divided by the arterial oxygen concentration.

Pearl index

SEE: Pearl index

pelvic index

The ratio of pelvic conjugate and transverse diameters multiplied by 100.

periodontal (Ramfjord) index

An extensive consideration of the periodontal status of six teeth by evaluating gingival condition, depth of gingival sulcus or pocket, appearance of plaque or calculus, attrition, tooth motility, and extent of tooth contact.
SEE: oral hygiene index

phagocytic index

The average number of bacteria ingested by each leukocyte after incubation of the leukocytes in a mixture of serum and bacterial culture.

physiological cost index

ABBR: PCI In sports medicine, the metabolic expenditure per unit of distance traveled. It is expressed as the number of heartbeats per meter traveled and is calculated by subtracting the resting heart rate from the exercise heart rate divided by the distance traversed.

Pneumonia Severity Index

pneumonia severity index A diagnostic scoring system for predicting the level of care a patient with pneumonia will require. It includes demographic factors (such as the patient's age, whether he or she resides in a nursing home); findings on physical examination (such as altered mental status, fever, tachycardia, and low blood pressure); laboratory data (including serum pH, glucose and sodium levels); and the presence of other illnesses (such as heart, lung, brain, liver, or kidney disease).
SYN: SEE: pneumonia PORT score.

ponderal index

The ratio of an individual's height to the cube root of his or her weight; used to determine body mass.
SEE: body mass index

proliferative index

ABBR: PI The proportion of cells within a tumor specimen that are actively reproducing. In general, as the number of replicating cells in a tumor increases, the cancer behaves more aggressively and the prognosis for the patient worsens.

index of refraction

1. The ratio of the angle made by the incident ray with the perpendicular (angle of incidence) to that made by the emergent ray (angle of refraction).
2. The ratio of the speed of light in a vacuum to its speed in another medium. The refractive index of water is 1.33; that of the crystalline lens of the eye is 1.413.
SYN: SEE: refractive index

refractive index

SEE: Index of refraction.

rapid shallow breathing index

ABBR: f/TV; RSBI The ratio of the respiratory rate (f) and the tidal volume (TV) of a patient treated with mechanical ventilation while breathing on a T-piece (or at minimal levels of positive airway pressure or pressure support). Levels less than 105/min/L indicate that a patient may be able to be weaned successfully from the ventilator and breathe unassisted.

Reid index

SEE: Reid index

resistance index

resistive index ABBR: RI The ratio of the blood flow through an artery during systole minus its blood flow during diastole, divided by the systolic flow. The RI is measured with doppler ultrasonography. When the diastolic flow is equal to the systolic flow, the RI = 0; and, when diastolic flow is entirely blocked, the RI = 1. The RI can exceed 1 when there is backwash from an organ into the artery during diastole.

respiratory index

ABBR: RI SEE: Alveolar/arterial gradient.

respiratory disturbance index

A measurement of the number of disordered breathing cycles during sleep. Sleep disordered breathing, which includes both apneas and hypopneas, results in daytime fatigue. It is also associated with an increased prevalence of cardiovascular disease. VAR: respiratory event index.

sacral index

The sacral breadth multiplied by 100 and divided by the sacral length.

satiety index

The relative degree to which different foods of the same caloric value satisfy hunger.

saturation index

In hematology, the amount of hemoglobin present in a known volume of blood compared with the normal amount.

Science Citations Index

ABBR: SCI An electronic database of scientific journal articles published and referred to by other authors.
The Index is a proprietary product of the Thomson Corporation.

shock index

1. The systolic blood pressure divided by the heart rate.
2. The heart rate divided by the systolic blood pressure.

sulcus bleeding index

ABBR: SBI A sensitive measure of gingival condition that involves probing of all sulci. The score is based on six defined criteria. It is calculated by counting the number of sulci with bleeding, dividing by the total number of sulci, and multiplying by 100.

sunscreen protective factor index

In preparations for protecting the skin from the sun, the ratio of the amount of exposure needed to produce a minimal erythematous response with the sunscreen in place divided by the amount of exposure required to produce the same reaction without the sunscreen. This index assesses the ability of sunscreens to block ultraviolet B (short-wavelength) rays but does not measure the protective effect of sunscreens against ultraviolet A (long-wavelength) rays.
SEE: erythema dose

therapeutic index

The maximum tolerated dose of a drug divided by the minimum curative dose.
SYN: SEE: therapeutic profile; SEE: therapeutic window

thoracic index

The ratio of the thoracic anteroposterior diameter to the transverse diameter.

Vancouver scar index

SEE: Burn scar index.

ventilation index

1. A calculation to determine the severity of respiratory illness (acute lung injury and/or respiratory distress syndrome) in critically ill patients. The VI is the partial pressure of arterial CO2 multiplied by the peak airway pressure multiplied by the rate of ventilation, all divided by 1000.
Symbolically, the VI is calculated as follows: VI = [RR × (PIP − PEEP) × PaCo2]/1000.

2. In environmental science, a measure of air pollution based on the speed of the wind and the height of the column of air in which smoke or other pollutants mix.

vital index

The ratio of the number of births to the number of deaths in a population over a stated period of time.

Western Ontario McMaster Osteoarthritis Index

SEE: Western Ontario McMaster Osteoarthritis Index