Related Experiment Video
Updated: Oct 23, 2025
Precision Implementation of Minimal Erythema Dose MED Testing to Assess Individual Variation in Human Inflammatory Response
Published on: October 3, 2019
Ideal proportion of the population to be patch tested: How many should we be doing?
Avad A Mughal1, Ashima Lowe2, Sofia Hadjieconomou2
1Dermatology Department, Neath and Port Talbot Hospital, Port Talbot, UK.
Background:
How many patients should we be patch testing? A previous study suggested that the minimum proportion of a population to be patch tested for allergic contact dermatitis was 1:700 annually.
Objectives:
To evaluate if the current minimum rate for patch testing has changed over the 20 years since the previous study in order to maximize the value.
Methods:
In cooperation with the British Society for Cutaneous Allergy, a proforma for collation of retrospective data between January 2015 and December 2017 was sent to patch-test centers in the United Kingdom (UK) and the Republic of Ireland (ROI). The number of positive tests was analyzed against the proportion of population tested to see what proportion of the population would yield the greatest number of positive results.
Results:
Responses from 11 centers showed that the minimum number needed to patch test had increased to 1:550 per head of population per year using the current criteria.
Conclusions:
In agreement with previous studies, we should be patch testing more people than we are. We could reduce the threshold for referral of patients we patch test to derive the most benefit from this investigation.
Related Concept Videos
01:20Sample Proportion and Population Proportion
01:24Testing a Claim about Population Proportion
There are two methods of testing a claim about a population proportion: (1) Using the sample proportion from the data where a binomial distribution is approximated to the normal distribution and (2) Using the binomial probabilities calculated from the data.
The first method uses normal distribution as an approximation to the binomial distribution. The requirements are as follows: sample size is large...
01:49Hardy-Weinberg Principle