Definition community intervention trial

However, the outcome can instead be related to other changes that occurred around the same time as the intervention, e. The change can also represent a natural variation e. Thus, the outcomes observed in such studies cannot be reliably attributed to the specific intervention, making this a weaker design than RCT. If two or more interventions are available for a particular disease condition, the relevant question is not only whether each drug is efficacious but also whether a combination of the two is more efficacious than either of them alone.

Let us think of two interventions: A and B. The participants are randomly allocated to one of four combinations of these interventions — A alone, B alone, both A and B, and neither A nor B control. This design allows i comparison of each intervention with the control group, ii comparison of the two interventions with each other, and iii investigation of possible interactions between the two treatments whether the effect of the combination differs from the sum of effects of A and B when given separately.

As an example, in a recent study, infants in South India being administered a rotavirus vaccine were randomly assigned to receive a zinc supplement and a probiotic, only probiotic with zinc placebo , only zinc supplement with probiotic placebo , or neither probiotic placebo and zinc placebo.

This design allows the study of two interventions in the same trial without unduly increasing the required number of participants, as also the study of interaction between the two treatments. Each participant first receives one intervention usually by random allocation, as described above. Most often, the two interventions are separated by a washout period to get rid of the effect of the first intervention and to allow each participant to return to the baseline state.

For example, in a recent study, obese participants underwent two 5-day inpatient stays — with a 1-month washout period between them, during which they consumed a smoothie containing g walnuts or a macronutrient-matched placebo smoothie without nuts and underwent measurement of several blood analytes, hemodynamics, and gut microbiota. However, this design can be used only for disease conditions which are stable and cannot be cured, and where interventions provide only transient relief.

For instance, this design would be highly useful for comparing the effect of two anti-inflammatory drugs on symptoms in patients with long-standing rheumatoid arthritis. Sometimes, an intervention cannot be easily administered to individuals but can be applied to groups. As an example, a study in Greece looked at the effect of providing meals in schools on household food security.

However, such studies need a somewhat larger sample size than individual-randomized studies and the use of special statistical tools for data analysis. National Center for Biotechnology Information , U.

Journal List Perspect Clin Res v. Perspect Clin Res. When they are randomized, community intervention trials are known as cluster randomized controlled trials CRCTs. Whether randomization is used or not, if the solution is shown to be beneficial, our commitment is to extend it to all communities in the sample. Wayne W. Intervention Studies Clinical Trials.

Types of Intervention Studies Individual versus Group Community Trials Most trials are conducted by allocating treatments or interventions to individual subjects , i. For example, investigators recently compared the effectiveness of glucosamine and chondroitin and several other drugs in their ability to relieve symptoms of osteoarthritis.

Subjects were randomly assigned to receive one of several possible treatments, and they were followed and assessed for pain relief and other measures. In contrast, group trials allocate the intervention to groups of subjects. Why is the community approach essential? Most common health problems amenable to prevention have strong environmental, cultural, lifestyle, and behavioral components.