Screening…An important public health tool

On routine health check-up of Mr X, the doctor suggested to undergo screening for Diabetes. Mr. X was baffled; in all of his 35 years of existence, he had been perfectly healthy. He did not understand what screening was and why he should be screened. He asked the doctor to explain, regarding the need for screening tests, and underwent the tests once he understood the need and importance of screening.

Screening is an important public health measure in disease control. In simple words, screening identifies presumptively, previously unrecognised disease in apparently healthy population by the use of rapidly applicable tests or examinations. A screening test is not intended to be diagnostic and persons who test positive often require further diagnostics for confirmation of the diagnosis.

Screening is of utmost importance in non-communicable diseases like Diabetes, Hypertension, Cardiovascular diseases and Cancer. These diseases often are asymptomatic in early phases but the disease process is active even in asymptomatic people which often manifests at a later stage as a complication. For example, a person with diabetes may have the disease for many years without his knowledge and may be diagnosed only when he or she has a complication like a diabetic foot or heart disease. Screening tests are available for communicable diseases also.

Theoretically, screening is a suitable opportunity to find undiagnosed disease in apparently healthy individuals. Let’s take the example of a person with diabetes again. With a screening test, the person would have been diagnosed much earlier in the disease process and hence may be given treatment to avoid disease progression which would otherwise have led to end organ damage. Also the complication would have been avoided, saving the unnecessary costs of hospitalisation and specialised care, apart from saving the patient from the agony of the condition.

However, screening in practice is wrought with practical difficulties. From the provider’s point of view, screening tests have to be cheap, easily performable and should be able to correctly screen the population for the disease in question. At the population level, the problems are much more complex with psychosocial implications. Many people are known to refuse screening, especially for diseases like cancer. Even when screening tests are done and results are positive, people often are known to refuse the follow up diagnostics.

Nevertheless, screening is an invaluable public health measure to reduce the health cost, control spread of diseases and reduce human suffering. However it has to be done in a well-planned fashion. The selection of the screening test and the population for screening should be evidence based. Well planned population mobilisation must be done prior to any screening activities and counselling services should be made available for patients who may test positive. Mainstreaming of the screening programmes through public health infrastructure is a measure which can make the tests available and acceptable to our population.

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