(LML) What every Indian should know about leprosy

Leprosy Mailing List – June 22,  2015

Ref.:    (LML) What every Indian should know about leprosy

From:  Joel Almeida, Kochaikanal, India

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Dear Pieter,

 

I must say to Dr. Warren (LML, 21-06-2015): “I.S.” (I’m sorry) for not expanding abbreviations. I will try to make amends.

DALY (disability adjusted life year) is a measure of disease burden.  It is expressed as years lost to disability (or premature death) from a particular cause. It aggregates years lost to disability in individuals. The entire stream of morbidity arising from that condition is counted in DALYs. (However, when conditions co-exist and are entangled, only one of them can be taken as the prior cause).

For example, in leprosy, let’s imagine a newly occurring MB (multibacillary) case (Rani) who remained in virtually perfect health apart from thickened nerves, and started on MDT (multi-drug therapy) aged 30 years.  Her nerves developed “silent” neuritis just as she completed her 12 months of MDT.  She lived several km (kilometres) from the nearest health centre. Unfortunately, she developed signs of peripheral neuropathy in all 4 limbs and both eyes, and developed the deformities characteristic of leprosy.  She scraped together the bus fare to attend the health centre, and borrowed the even greater bus fare to attend a referral centre: once the deformities became too difficult to disguise.  A course of steroids failed to restore her nerve function.  She was then disowned and ostracised owing to the visible deformities of leprosy.  She went to a big city and survived by begging, suffering chronic depression and anxiety with intermittent attempts at suicide. Her loss of ability (to live a full and happy life) is reduced by an estimated 60% (averaged across the years of her life following the silent neuritis).

Rani, as a human being, could live to the age of 80 - as human beings do when they are spared disease.  From the age of 31 onwards her life was blighted by the nerve damage of leprosy.  She lost 60% of her remaining entitlement of 49 years of life to disability (physical and emotional) - all attributable to leprosy. She lost 0.6 x 49 years = 29.4 DALYs to leprosy.

To ordinary people, and ordinary public health experts, Rani is a human being with DALYs lost to leprosy.  (Although to the keepers of MDT registers, she is non-existent: having completed MDT.)  To ordinary public health experts Rani’s lost DALYs are attributable to leprosy. Her disabilities were caused by leprosy. They were not caused by ovarian cancer or Alzheimer’s disease.  They were caused by leprosy.  And DALYs are the most important criterion being used for investment decisions in the health sector.  If we want to serve leprosy patients well, we have to get our DALYs right.  Professionals in other diseases do it, and the populations they serve benefit from it.

If we studied a random sample of people affected by leprosy, we would arrive at estimates of DALYs lost for each of them. Those with self-healing lesions would lose almost no DALYs.  Those with localised leprosy would lose fewer DALYs than Rani did.  Even some of those with disseminated leprosy might lose fewer DALY’s than Rani did. 

Summing across the individuals in our random sample, we would arrive at an estimated typical (or average) DALY loss for each of these 3 presentations of leprosy. Adding together the DALY loss for the 3 presentations would give us an estimate of the DALYs lost to leprosy across our random sample of individuals.  We could then extrapolate from our random sample to the population from which we drew our sample.

We ought to be estimating the burden of disease in leprosy, in DALYs, along these lines:

Annual incidence rate of leprosy x remaining entitlement of life in years for each type of leprosy x average loss of ability attributable to each type of leprosy (whether on or off the MDT register) during that remaining entitlement of life summed across the types of leprosy.

When we say an intervention is expensive or inexpensive, we could usefully express it in terms of DALY loss averted per rupee (or real or pound sterling etc.) invested.  Sometimes an intervention can save a huge number of years otherwise lost to disability.  That can make it highly cost-effective even if it seems expensive at first sight.

 

Regards,

 

Joel Almeida

 

some more abbreviations used previously:

WHO – World Health Organization

NTD – Neglected Tropical Diseases

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LML - S Deepak, B Naafs, S Noto and P Schreuder

LML blog link: http://leprosymailinglist.blogspot.it/

Contact: Dr Pieter Schreuder << editorlml@gmail.com

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