India's disease transition

Across the world and over time, growth and development transform what people get sick and die of.

The World Health Organisation splits the causes of death into three broad categories:

(i) communicable, maternal, perinatal and nutritional conditions - these include vector-borne diseases like malaria, as well as deaths from conditions associated with pregnancy, childbirth and early life
(ii) non-communicable diseases - these include cardio-vascular diseases, cancers and other diseases that do not spread through contact, air or vectors, and
(iii) injuries - these include homicides, self-harm and road accidents.

The epidemiological transition

When a group - either geographical or social - is at low levels of income with poor nutrition and low levels of access to a clean environment and healthcare, communicable diseases and conditions related to childbirth account for most deaths. As groups get richer and older, deaths from these causes become more preventable and less common. As a result, the relative share of deaths from non-communicable diseases such as heart disease and cancer begins to rise.

India is in the midst of this transition, a moment that in public health is called the epidemiological transition from communicable diseases and conditions surrounding childbirth to non-communicable diseases as the leading cause of mortality.

The epidemiological transition in Indian states

The extent of the shift from communicable diseases being the leading cause of death to non-communicable diseases varies by region within India.

Communicable diseases still account for nearly 30% of deaths in India's poorest states^[1]. On the other hand, non-communicable diseases now account for significantly over half of all death in India's more developed states.

These differences play out within regions too. While just 10% of deaths in southern states are from communicable diseases and conditions around childbirth, this proportion is nearly 30% for central Indian states. Non-communicable diseases meanwhile account for over half of deaths in India's southern states.

Communicable diseases

Roughly 10 million people die every year in India. Of these, a little over 17% or roughly 1.7 million deaths are from communicable diseases.

Among identified communicable diseases, respiratory infections including influenza and pneumonia are the leading cause of death, and particularly deadly to the elderly. Diarrhoeal diseases are the next largest cause of death among communicable diseases and killed an estimated 330,000 Indians in 2018, but the risk of death from diarrhoeal disease has steadily fallen. Tuberculosis remains a key cause of death in adults and is the communicable disease that contributes to the most deaths in Indians aged 15-70.

Communicable diseases are particularly deadly for the young and account for a third of deaths in children under the age of 14 in India.

Communicable diseases are often difficult to diagnose both during treatment and after death in low-income settings where laboratory testing is not always possible. As a result, the largest share of deaths among communicable diseases are from "fever of unknown origin" according to India's official statistics. Over time, the share of deaths attributed to this grouping is slowly declining, as the specific causes of death .

Noncommunicable diseases

From middle age onwards, non-communicable diseases led by heart disease become the leading cause of death, as the relative risk from infectious diseases declines, and age and factors including obesity and hypertension put people at greater risk.

As India gets richer and simultaneously ages, non-communicable diseases now account for two out of three deaths in India. Among non-communicable diseases, heart disease^[2] is the largest contributor to Indian mortality, followed by non-communicable respiratory diseases.

Cancer kills nearly 7% of Indians every year, with a higher contribution to mortality among those in their late 40s and early 50s in particular. Nearly one in five deaths among women aged 45 to 54 are from cancer.

Deaths from causes other than disease: Injuries

Roughly one in ten deaths in India is from causes that do not have to do with disease but are from injuries, more so among men. Late childhood and early adulthood are the only periods of time in India where the greatest risk of death is not from disease, but from either injury or self-harm. For older children (age 5-14), injuries as a result of falls, drownings and other accidents become an important cause of mortality, accounting for more than one in five deaths. Among young women (aged 15-29), self-harm accounts for the most deaths. Among young men (age 15-29), road accidents become the leading cause of death.

Assigning causes of death in India

For this piece, we use estimates for cause of death based on India's Sample Registration System's annual Causes of Death report which studies around 140,000 deaths across a sample population of over 8 million people every year. The latest report is for the period 2017-2019.

SRS enumerators ask a household member to describe in their own words and language the symptoms and circumstances around a death in the household, and two trained doctors later evaluate the description and code up the cause of death - a process called "verbal autopsy" that was designed for low-income settings.

However, many deaths cannot be properly classified even through the SRS - over 12% of deaths (and more than 15% in the case of women) were classified as "ill-defined" in the latest SRS report. Even within communicable diseases, the largest share of deaths are attributed to "fever of unknown origin" without a specific cause identified.

Additionally, the SRS does not make its raw data available. As a result, some deaths are grouped into categories like "other bacterial infections", but cannot be disaggregated by us. For this piece (unless stated otherwise), DFI is looking at clearly and individually identified causes of death. Data on all causes of death as listed by the SRS is also available in the Explorer at the end of the piece.

For more on mortality measurement, read our piece on it here.

Use our data explorer to look at all causes of death by age group and gender

[1] The Sample Registration System classifies Bihar, Jharkhand, Madhya Pradesh, Chhattisgarh, Orissa, Rajasthan, Uttar Pradesh, Uttarakhand and Assam as "states have had historically higher child mortality indicators, higher poverty levels and lower life-expectancy and other indicators than most other states"

[2] Ischaemic heart disease in particular - also called coronary heart disease or coronary artery disease, it refers to cardiac problems caused by narrowed heart (coronary) arteries that supply blood to the heart muscle