The global inverse care law: a distorted map of blindness


“Eye care for all” is the motto of this year’s World Sight Day. But there are stark global inequalities in access to eye care. In 1971, Hart described the, ‘Inverse Care Law’ as the availability of good medical care varying inversely with the need for it in the population served. Hart was describing the situation in the National Health Service in Great Britain at the time in which he practiced as both a General Practitioner and an epidemiologist.
Two recently published articles demonstrate the ‘Inverse Care Law’ on a global level. The prevalence of blindness worldwide in 2010 was reported by the WHO and verified that low- and middle-income countries, as expected, have the highest prevalence of blindness and visual impairment. In stark contrast to this, a more recent report describes the,“Number of ophthalmologists in training and practice worldwide” providing global data for the number of ophthalmologists per county and demonstrates that despite a growing number in practice the gap between need and supply is widening.
The situation is also magnified within individual countries of high, middle and low-income. For example, in France, an inverse correlation was found between the number of ophthalmologists and the prevalence of low vision for subjects of similar age and socio-professional category and another example is in Kenya where of the 86 practicing ophthalmologists, 43 are based in Nairobi (personal correspondence). That equates to 50% of the countries ophthalmologists serving 8% of an already underserved population.
We have developed two cartograms to depict the data from these two papers using Gastner & Newman diffusion-based method. This allowed us to create density-equalised maps based on the absolute values provided in the papers. In the maps, each of the reference areas (WHO regions and countries) is resized according to these values. Larger areas represent higher numbers and smaller areas proportionally smaller data values:

Cartograms of Blindness and Opthmamologists
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Global Mobile Phone Users: A Decade of Changes

A global shift in predominance of mobile/cell phone ownership in the last decade has seen low-income countries reach near ubiquitous levels. Using 11 years of compiled census data from each country worldwide, Andrew Bastawrous, Iain Livingstone and I analysed the global picture of cell phone ownership and used density-equalizing cartograms to depict this change. This cartogram animation shows a decade of change in the use of mobile phones:

Cartogram animation of global mobile phone subscriptions between 2000 and 2011
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Ebola epidemic (update)

As stated by the Centers for Disease Control and Prevention (CDC), “the 2014 Ebola epidemic is the largest in history, affecting multiple countries in West Africa”. Since the first map series published here in August, an additional 5367 cases and 2294 deaths have occurred, resulting in a total case count of 7492 and a total number of deaths of 3439 for the current outbreak according to the most recent updated published on October, 3rd. These significant changes change the shapes of the cartograms published six weeks ago, not least because the current outbreak exceeds all previous Ebola cases counted since 1977, as the following maps show using the most recent data:

Cartogram visualisations of Ebola virus cases
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Ebola Outbreak

The recent outbreak of Ebola in West Africa has not been brought under control since it became part of international attention early 2014. As of 15 August the suspected and confirmed cases added up to 2127, leading to 1145 deaths in the region (source: Centers for Disease Control and Prevention).
The outbreak is not only unusual in its absolute numbers of cases and deaths (before the current outbreak a total of 2387 cases and 1590 deaths have been recorded by the World Health Organization since the virus was discovered in 1976), but also in its geographical patterns: While WHO obervations in the past mainly occurred in the tropical regions of Sub-Saharan Africa (affecting mainly Congo, DR Congo, Gabon, Sudan and Uganda), the current and by far largest outbreak is observed in the previously unaffected countries of Sierra Leone, Guinea, Liberia and (less servere) Nigeria). The following map shows not only that Ebola is restricted to Africa, but to a very small part of the continent. It shows the countries of the world resized in a Worldmapper-style cartogram according to the total number of cases in each country in 2014 (to date):Map of the 2014 Ebola Outbreak in West Africa - total cases as of August, 14thTo put the outbreak into further context, the following maps show the death counts of all Ebola outbreaks to date, as well as two split maps of deaths in 2014 and pre-2014: Continue reading

A mapping sequence for malaria and mosquito nets in Africa

Roll Back MalariaThe upcoming annual World Malaria Day on the 25th of April is one of the most visible international activities to tackle the problem of a disease that today is mainly a problem on the African continent. Beyond that day, activists from public sector as well as from many private organisations have regular meetings to find solutions for a disease that UNICEF describes as both preventable and curable. Continue reading

A Tale of Two Cities: London’s Health Inequalities

London is a special city, London is incredibly diverse and London has its own unique health problems. In 2012 the London Deanery, in partnership with the British Medical Association, is hosting a series of seminars that look to provide […] an opportunity to debate some of the key healthcare issues that face the capital in 2012.” This extract from the announcement of the Metropolitan Medicine 2012 seminar series highlights the need to take a closer look at London’s position within the United Kingdom, as the challenges that the city faces are probably not different, but certainly unique to the problems that currently exist in the health sector of the country.
A tale of two cities: London’s health inequalities was the title of my contribution to the seminar series. In my presentation I highlighted some of the problems that are part of that issue, explaining how social and health inequalities are inevitably intertwined. London is unique in the social landscape, but also part of the processes that shape the UK, which I demonstrated in a series of maps in my slides that accompanied my talk: Continue reading