Natural history group

First usage

In 1863, Austin Flint (1812–1886) in his report of the first-ever trial that directly compared the efficacy of a placebo treatment with that of an active treatment, spoke of "the natural history of [an untreated] disease".

Third arm

The natural history group is often referred to as the third arm of a controlled drug trial, from the simple notion that a trial constructed in this way has three, rather than two arms (the "active" and "placebo" groups).

The observed outcomes within this group are then compared with the outcomes manifested by a group that has been given the active drug, and with that manifested by a second group who have been given a dummy, placebo drug (thus, the natural history group is the trial's "third arm").

For example, in the laboratory setting it is possible to conduct trials using three randomly selected, equally matched groups:

(1) the natural history (NH) group or untreated group, which receives no treatment of any kind;

(2) the placebo group, which receives an inert treatment that simulates the active one;

(3) the active treatment, which receives the real treatment.

The comparison between the placebo and the natural history group allows us to detect and measure the placebo effect.}}

Notes

References

• Flint, A., "A Contribution Toward the Natural History of Articular Rheumatism, Consisting of a Report of Thirteen Cases Treated Solely with Palliative Measures", American Journal of the Medical Sciences, Vol.46, (July 1863), pp. 17–36.

References

1. (1863). "The American journal of the medical sciences".
2. Colloca, L., Finniss, D.G. & Benedetti, F., "Placebo and Nocebo", pp.499–514, in Rice, A., Howard, R., Justins, D., Miaskowski, C., Newton-John, T. (eds.), ''Clinical Pain Management (Second Edition), Volume Three: Practice and Procedures'', Hodder Arnold, (London), 2008, p.502.