p24 ANTIGEN
A core protein making up the nucleocapsid of the HIV Virus, p24 was thought at one time to be a surrogate marker for disease progression. Now it is recognized that some long term asymptomatics have relatively high elevations of p24, while others die never having been positive (anything less than 10 picograms/mole is effectively negative)

P & P COMMITTEE
See "Publications and presentations committee"

P VALUE
The probability of obtaining a given outcome due to chance alone. For example, a study result with a significance level of p<0.05 implies that 5 times out of 100 the result could have occurred by chance.

p24 ANTIGEN
The core protein fragment of HIV. The p24 antigen test measures this fragment in the bloodstream. A positive result for the p24 antigen suggests HIV replication, and may mean the individual has a higher chance of developing AIDS in the future.

PACKAGE INSERT
A document approved by the Food and Drug Administration and furnished by the manufacturer of a drug for use when dispensing the drug, which indicates approved uses, contraindications, and potential side effects. See "Label Insert."

PAHO
Pan American Health Organization.

PALLIATIVE
A treatment which provides symptomatic relief, but not a cure.

PANCREATITIS
Inflammation of the pancreas. Pancreatitis is often characterized by abdominal pain, nausea/vomiting and elevated triglyceride and amylase levels. Pancreatitis, which can be fatal, is a known side effect of ddI

PANDEMIC
Referring to an-epidemic disease of widespread prevalence.

PAP SMEAR (PAPANICOLOU SMEAR)
A specimen of vaginal or cervical cells placed on a slide and examined under the microscope for abnormal development.

PAPILLOMAVIRUS
A family of papova viruses associated with sexually transmitted diseases, including condylomata. Certain papillomavirus variants have also been associated with cervical cancer, particularly in HIV infected women.

PAPULE
A small raised bump or protrusion on the skin

PARALLEL TRACK
A system of distributing experimental drugs to patients who are unable to participate in ongoing clinical efficacy trials and have no other treatment options.

PARASITE
A plant or organism that lives on or in the host, deriving nourishment from it. Some cause inflammation, but others cause infection and destroy tissue. Human parasites include fungi, yeast, bacteria, protozoa, worms and viruses.

PARENTERAL
Not through the mouth. Intravenous, intramuscular, and intradermal administration are all parenteral

PARESTHESIA
Abnormal sensations: numbness, tingling, burning.

PAROMOMYCIN (HUMATIN)
An antibiotic used for treating intestinal infections.

PARTIALLY BLINDED CLINICAL TRIAL
1. A clinical trial in which some, but not all, of the study treatments are administered in a single- or double-blinded fashion. 2. A clinical trial in which some, but not all, of the staff in a clinic are blinded to treatment assignment.

PARTICIPANT
Study participant.

PASSIVE IMMUNOTHERAPY/PASSIVE IMMUNIZATION
Infusion of antibodies from another individual. AS distinguished from actively stimulating an immune response in the recipient

PATHOGEN
Any disease-producing microorganism or material.

PATHOGENESIS
The natural evolution of a disease process in the body without intervention (i.e., without treatment); Description of the development of a particular disease, especially the events, reactions and mechanisms involved at the cellular level.

PATIENT CLOSE-OUT
The process of separating patients from a clinical trial at the end of treatment and follow-up.

PATIENT CLOSE-OUT STAGE
The stage of a trial in which patients leave a trial. The end of treatment and follow-up.

PATIENT FOLLOW-UP
A process involving periodic contact with patients enrolled in a clinical trial for the purpose of administering the assigned treatment(s), observing the effects of treatment(s), modifying the course of treatment(s), or for collecting required data.

PATIENT IDENTIFICATION NUMBER
A unique sequence of numbers, or numbers and letters, that are used to identify a patient.

PATIENT POPULATION
Study population.

PATIENT RECRUITMENT
The process of identifying suitable patients for enrollment into a clinical trial.

PATIENT RECRUITMENT GOAL
The number of patients scheduled to be enrolled into the trial. Usually set before the trial starts, or shortly thereafter, via a sample size calculation or via practical considerations.

PCP
See "Pneumocystis Carinii Pneumonia."

PCR (POLYMERASE CHAIN REACTION)
A highly sensitive test that can detect and/or DNA fragments of viruses or other organisms in blood or tissue. PCR works by repeatedly copying genetic material using heat cycling, and enzymes similar to those used by cells.

PEDIATRIC
Relating to the medical specialty concerned with the development, care and treatment of children from birth through adolescence.

PELVIC INFLAMMATORY DISEASE (PID)
A painful gynecological condition usually caused by infection, where disease spreads upward from the vagina into the pelvic cavity.

PENTAM
Brand name of Pentamidine.

PENTAMIDINE
An antibiotic effective in an IV formulation against PCP. An aerosolized form is used to prevent PCP.

PEPTIDE
A short string of amino acids. Peptides are small proteins.

PERINATAL
Relating to the period around the time of birth.

PERIPHERAL
Toward the outside, or at the extremities.

PERIPHERAL NEUROPATHY
A disorder of the nerves that usually involves the feet or hands and sometimes the legs, arms and face. Symptoms may include numbness, a tingling or burning sensation, sharp pain, weakness and abnormal reflexes.

PEYER'S PATCH
Lymphatic tissue lining the intestines. One of the largest areas of lymphatic tissue in the body. May take over some of the role of the thymus in adults

pH
A term used to describe the acidity or alkalinity of a solution. It directly measures the hydrogen concentration of a solution. If the pH is low the solution is acidic; if high, alkaline.

PHAGOCYSTOSIS
The consumption and destruction of foreign materials by white blood cells like macrophages

PHARMACOKINETIC
Concerning the study of how a drug is processed by the body, with emphasis on the time required for absorption, duration of action, distribution in the body and method of excretion.

PHARMACEUTICAL AND REGULATORY AFFAIRS BRANCH
That office at NIAID responsible for coordinating communication with FDA and industry. In particular, PRAB is concerned with drugs under IND status, and with prompt reporting, summary, and analysis of adverse events in NIAID sponsored trials.

PHASE I TRIAL
The first stage in testing a new drug in humans. Performed as part of an approved Investigational New Drug Application under Food and Drug Administration guidelines. The studies are usually done to generate preliminary information on the chemical action and safety of the drug using normal healthy volunteers. Usually done without a comparison group.

PHASE II TRIAL
The second stage in testing a new drug in humans. Performed as part of an approved Investigational New Drug Application under Food and Drug Administration guidelines. Generally carried out on patients with the disease or condition of interest. The main purpose is to evaluate activity, and possibly provide preliminary information on treatment efficacy and to supplement information on safety obtained from phase I trials. Usually, but not always, designed to include a control treatment and random allocation of patients to treatment.

PHASE II/III
A special classification arising from the AIDS context where greater testing of efficacy occurs earlier.

PHASE III TRIAL
The third and usually final stage in testing a new drug in humans. Performed as part of an approved Investigational New Drug Application under Food and Drug Administration guidelines. Concerned primarily with assessment of dosage effects and efficacy and safety. Usually designed to include a control treatment and random allocation to treatment. Once this phase is completed the drug manufacturers may request permission to market the drug by submission of a New Drug Application to the Food and Drug Administration, assuming the results of the phase I, II and III trials are consistent with such a request.

PHASE IV TRIAL
Generally, a randomized controlled trial that is designed to evaluate the long-term safety and efficacy of a drug for a given indication and that is done with Food and Drug Administration approval. Usually carried out after licensure of the drug for that indication.

PICO-
Prefix meaning a one one-trillionth, as in picogram, a trillionth of a gram.

PID
See "Pelvic Inflammatory Disease"

PILOT STUDY
A preliminary study designed to indicate whether a larger study is practical. See "Feasibility Study."

PHOSPHORYLATION
The process of adding phosphorus to a compound. Often done within the body by enzymes named "kinases". The nucleoside drugs, like AZT, ddI, ddC, etc. all need to be phosphorylated in the body before they become active.

PID
Patient identification number. A unique identifier that refers to a particular patient, yet preserves confidentiality for record keeping

PIETC
See "Protocol Implementation, Education and Training Committee"

PLACEBO
A pharmacologically inactive agent given to a patient as a substitute for an active agent and where the patient is not informed whether he is receiving the active or inactive agent.

PLACEBO-CONTROLLED CLINICAL TRIAL
A clinical trial in which patients assigned to the control treatment receive a placebo.

PLACEBO EFFECT
The effect produced by a placebo due to the expectations of the patient. The effect in placebo-controlled clinical trials is generally measured by comparison of the effect observed in patients receiving the placebo treatment with the effect observed in patients receiving the active treatment.

PLACENTA
A combination of fetal and maternal cells that serves as the organ of exchange for nutrients and other chemicals between mother and fetus during pregnancy.

PLATELET
Blood cells that are essential to clotting.

PML
See "Progressive Multifocal Leukoencephalopathy"

PNEUMOCYSTIS CARINII PNEUMONIA
An opportunistic pneumonitis often seen in HIV-infected patients. PCP generally produces a dry, hacking cough. Although previously thought to be a protozoa, and responsive to anti-protozoal treatment, recent genetic analysis suggest that p carinii is closer to the funguses.

PO
Abbreviation for "by mouth" (as opposed to Intravenous, intramuscular, etc.).

POLYNEUROPATHY
Neuropathy involving a number of different nerves

POSTERIOR
Rear side, or behind.

POST-HERPETIC NEURALGIA (PHN)
Literally "pain following herpes." The term is usually applied to the severe pain that sometimes follows the healing of herpes zoster lesions.

POST HOC ANALYSES
Analyses conducted after the results are available that were not defined before the start of the trial. Such analyses are particularly prone to false-positive claims or type I error.

POSTHUMOUS
After Death

POST-MARKETING SURVEILLANCE
Term used by the Food and Drug Administration to characterize any procedure, implemented after licensure of a drug for a given indication, that is designed to provide information on the actual use of the drug for that indication and on the occurrence of related side effects. The surveillance usually involves survey techniques rather than controlled trials.

POST-MORTEM
After death, or after the event.

POST-PARTUM
After giving birth.

POST-STRATIFICATION
The process of classifying patients into strata after they have been enrolled in the study‹usually for data analysis purposes.

POWER
The probability of finding a treatment effect that actually exists, or of rejecting the null hypothesis when the alternative hypothesis is in fact true. In clinical trials, the power of the study design is the ability of the study to detect a postulated difference between treatment groups if it in fact exists. For example, if there is "something going on" in the study, does the study design have the power to demonstrate it?

PPD
See "Purified Protein Derivative", also an acronym for the clinical site monitoring group for the CPCRA

PRAB
See "Pharmaceutical and regulatory affairs branch"

PRECLINICAL
Generally refers to research that has been done before a compound is tried on humans, i.e. in vitro and animal studies

PREMATURE TERMINATION
Early termination of a trial before data are sufficiently strong to be convincing.

PRENATAL
Relating to the period before birth.

PRERANDOMIZATION EXAMINATION
Any examination that is part of the evaluation process of a patient for enrollment into a trial and that is carried out before the randomization examination.

PRERANDOMIZATION VISIT
Any visit made to the clinic by a potential study patient for the purpose of evaluation for enrollment into the trial and that takes place prior to the randomization visit.

PRESUMPTIVE
Presumed. In the context of diagnosis, one that is not definitely made, but where signs and symptoms make it exceedingly likely to be the proper one, even without confirmatory evidence. Diagnosis of CMV retinitis by characteristic appearance, without using a biopsy is an example if a presumptive diagnosis.

PRIMARY DRUG RESISTANCE (PDR)
Resistance of bacteria or other pathogens to drugs which exists prior to the beginning of treatment.

PRIMARY OUTCOME
1. The event or condition the trial is designed to ameliorate, delay, or prevent. 2. The actual occurrence of a primary event in a study patient.

PRIMARY OUTCOME VARIABLE
The outcome variable that is designated or regarded as key in the design or analysis of the results of a trial. Generally, the variable used for sample size calculations in the design of the trial or, when no sample size calculation is made, for the main avenue of data analyses. The primary outcome monitored in interim analyses.

PRINCIPAL INVESTIGATOR
1. The designation used by the National Institutes of Health to denote the individual named on a grant who is responsible for directing the proposed research. 2. The lead scientist in a research project. (Usage note: It is best to avoid use of the term to designate the head of a center in a multicenter trial. It should be used in such settings only when there is a single individual, such as the chair of the study, who is regarded by everyone in the trial as the principal investigator. Otherwise some other term, such as center director, should be used.)

PRN
Abbreviation meaning "Take as needed:, usually applied to prescription drugs.

PROCRIT
Brand name of Erythropoietin

PRODRUG
A chemical precursor of a drug that is converted into the desired substance in the body.

PRODROMAL
Pertaining to symptoms indicating the onset of a disease. May include symptoms prior to those adequate for accurate diagnosis.

PROGNOSIS
The probable future course of a disease.

PROGRESSION OF DISEASE
A common endpoint used in AIDS clinical trials. The entity "progression of disease" usually consists of new occurrences of non-recurrent AIDS-defining illnesses or death.

PROGRESSIVE MULTIFOCAL LEUKOENCEPHALOPATHY
A rapidly degenerative neurological condition associated with HIV, characterized by diffuse gray-matter pallor on CT, and no focal lesions. Thought to be associated with JC Papovavirus.

PROJECT OFFICER
1. The individual in the sponsoring agency who is responsible for dealing with technical, scientific, and programmatic aspects of a grant or contract-funded project. 2. Health scientist administrator in National Institutes of Health grant-funded projects.

PROKINE
Brand name of Sargramostim

PROPHYLACTIC TRIAL
A trial that is designed to assess the efficacy of a treatment procedure aimed at preventing the development or progression of a specific disease or condition.

PROPHYLAXIS
Treatment intended to preserve health and prevent the occurrence or recurrence of a disease.

PROSPECTIVE FOLLOW-UP STUDY
A study in which people with a specific attribute or characteristic are identified and then observed for some period of time thereafter for the occurrence of the outcome or condition of interest, usually disease or death. The study may or may not involve a comparison group. Clinical trials represent a special subset of prospective follow-up studies.

PROTEASE
An enzyme that cleaves proteins. HIV protease is required to separate the long gag-pol polyprotein into it's constituent parts during the process of viral replication.

PROTEASE INHIBITOR
A new class of experimental antiretroviral drugs that work by inhibiting the HIV protease. Some examples include Saquinavir, Indinavir, and Ritonavir.

PROTEIN
A large group of substances made up of amino acids that are formed naturally by plants and all living organisms. An essential human nutrient, proteins provide the structures essential for the growth and repair of living cells and tissue.

PROTOCOL
A detailed plan for studying a treatment for a specific condition.

PROTOCOL IMPLEMENTATION, EDUCATION AND TRAINING COMMITTEE
A group of CPCRA staff representing all of the sites, as well as the various contractors, who provides guidance to the steering committee in regard to all of the listed issues.

PROTOCOL MANAGER
The staff person at the CPCRA Statistical Center who is over all coordinator for a particular protocol. They serve as liaison between the protocol team and the senior statistician, resolve any ambiguities or questions, and in general take care of most of the day-to-day maintenance.

PROTOCOL MONITOR
The staff person at the CPCRA Statistical Center who is primary clinic contact, and who coordinates the flow of data between the sites and the statistical center.

PROTOZOA
A family of unicellular organisms including amoebas, that are the simplest form of animal life. Protozoa can be a cause of parasitic disease. In AIDS, Toxoplasmosis, Pneumocystis carinii, Giardia, and Cryptosporidium belii are among the most harmful protozoa.

PROVIRUS
Viral genetic material, in the form of DNA, that has been integrated into the host genome. HIV, when it is dormant in human cells, is in a proviral form

PRURITIC
Causing itching

PRURITUS
An itching rash

PUBLICATIONS AND PRESENTATIONS COMMITTEE
The group of CPCRA investigators who coordinate all publications using CPCRA data.

PULMONARY
Pertaining to the lungs.

PURIFIED PROTEIN DERIVATIVE (PPD)
The most common test for exposure to m. tuberculosis, the bacteria that causes TB. In the PPD test, a small amount of protein from TB is injected under the skin. If the patient has been previously infected, they will mount a delayed type hypersensitivity reaction, characterized by a hard red bump called an induration.

PURULENT
Infected and producing pus.

PYRIMETHAMINE (DARAPRIM)
An antibiotic used in treating toxoplasmosis, and rarely for the treatment or prophylaxis of PCP