Bringing population health back into primary health care

In 1974, four years before the International Conference on Primary Health Care (PHC) was convened in Alma-Ata, USSR, the Canadian Ministry of National Health and Welfare published the Lalonde Report, named after the incumbent Liberal Party health minister Marc Lalonde.

Taking its cue from Thomas McKeown’s findings on the historical decline of tuberculosis mortality in England and Wales, the Lalonde Report challenged the presumption that improvements in human health by and large flowed from advances in (bio)medical knowledge, feeding through to professional practice and individual care.

McKeown’s writings on the main drivers of population growth and mortality decline in the early industrialising countries spawned vigorous debates. In addition to economic growth and improvements in food intake and nutritional status which McKeown himself highlighted, others argued also for the population health impacts of birth spacing and family size, housing and sanitary reforms (sewage disposal), and clean water and safe milk supplies (pasteurisation and eradication of bovine TB from livestock herds).

Mortality from typhus fever, a major killer in the 19th century, had shown continuous decline over subsequent decades in the UK to the extent that by 1906, three years before Charles Nicolle had discovered that the body louse transmitted typhus, London County Council reported no more deaths from that disease. Typhus fever, closely associated with poverty, poor housing, overcrowding, and poor hygiene was much less common among the middle and upper classes in 19th century England. Its decline was arguably linked to the increased availability of public baths, wash-houses, and widening use of cotton clothing, particularly underwear, which allowed for improved personal cleanliness.

Sonja and John McKinlay similarly concluded from their historical analyses that the fall in infectious diseases between 1900–1973, which accounted for 69% of the overall decline in US mortality during that period, could only be explained to a very limited extent (about 3%) by medical intervention.

Given the limited evidence base at the time, the Lalonde Report might in retrospect perhaps be judged prophetic (or lucky), and may have restrained a more cautious technocracy professing evidence-based policy and practice. In any case, the thesis was reinforced by subsequent findings from Sweden, France, Ireland, and Hungary, which supported the view that social and environmental changes were the key factors in their decline in infectious mortality.

By the time of the Alma-Ata declaration, these findings from medical history and population health were resonating strongly with more contemporary experiences from community-based primary health care in China, Bangladesh, Kerala, and Cuba. Notably, both perspectives shared a similarly broad vision of disease causation, rooted in what might be called a social ecology of health and disease.

According to the Canadian Advisory Committee on Population Health, population health strategies in particular address the entire range of factors that determine health, in contrast to traditional health care focusing on risks and clinical factors related to particular diseases. Furthermore, population health strategies are designed to affect an entire population, rather than specific individuals with existing health problems or a significant risk of developing one.

By the late 1980s, critics had highlighted weaknesses in the arguments of McKeown, challenging the relative contributions of fertility and mortality changes to population growth during the period in question, along with the early conflation of TB mortality with pneumonia and bronchitis (affecting the timing of TB’s decline), the under-emphasis of water supply and sanitary reforms from the 1870s and onwards, and, to a lesser extent, the contribution of isolation and quarantine to the control and reduction of infectious disease. From the 1850s onwards the decline of child labour (and its associated early life effects on adult health) has more also been proposed as a contributory factor, but this too is contested.

On the limited contribution of medical interventions to population health however, there was much less disagreement. Simon Szreter, who had played a prominent role in the critical re-appraisal of McKeown’s work, summed up the consensus thus: ‘The medical profession’s scientific leaders have, since McKeown’s time, had to change their tack and concentrate on the future, rather than the past, as the field in which they can stake the claim that they can save humanity from all its ailments with science.’

In less grandiose terms, the claim might be more plausible in the less developed countries, which still had (and for many still continue to have) large burdens of infectious disease in the mid-20th century, at a time when modern biomedical science could in principle have had a more significant impact on public health and in patient care (with vaccines, antimicrobials, and control of disease transmitting organisms).

The availability of diagnostics and the ongoing campaigns for access to anti-retrovirals for instance testify to the potential impact of biomedical science for the public health control of the HIV pandemic. Access to lifesaving treatment for infected individuals is emphatically a moral and ethical imperative. But a public health approach to anti-retroviral treatment goes beyond an individual focus. Equally important, the availability of effective therapy may in some situations encourage those at high risk to come forward for voluntary testing, and hence reduce the pool of infected-but-unaware individuals who constitute one of the drivers of the pandemic.

It is nonetheless noteworthy that the population health perspectives pioneered and promoted by McKeown and Lalonde continue to be relevant to modern epidemics. The SARS epidemic outbreak of 2002–2003 subsided largely in the absence of reliable diagnostics, vaccines, or efficacious therapies, notwithstanding the rapid success in isolating and sequencing the SARS coronavirus. Its control was credited to established public health measures such as isolation, contact tracing, ring-fencing, and quarantines, and the economic and financial stakes involved ensured that SARS would not be a ‘neglected disease’. ¬¬¬¬

Likewise, the Nipah outbreak in Malaysia (1998–1999) was rapidly brought under control without vaccines or efficacious therapies once modes of transmission were established. The knowledge that Nipah encephalitis was linked to a newly recognised paramyxovirus (which could be transmitted through close proximity to live, infected pigs but not via insects, suspended airborne particulates, or contact with raw or prepared meats) allowed for its rapid control in humans, even as this control decimated the pig farming industry in parts of Southeast Asia.

Thirty years on, these more recent experiences demonstrate that modern biomedical science continues to have an integral role to play in informing the socio-ecological perspective underpinning public health care in the 21st century.

In appraising this contribution of modern biomedical science to disease control and population health, it is however useful to distinguish between its contribution to knowledge-based practices and coping responses as opposed to a focus on commodifiable consumables. This distinction (neatly exemplified in the Nipah example) is especially pertinent in ensuring that advances in biomedical science in support of public health care are not simply subject to the strategic priorities of market-driven research and product development, but are backed by publicly-funded and rationally deployed needs-driven research in the biomedical sciences.

* Chan Chee Khoon, Universiti Sains Malaysia. email: ckchan50[AT]yahoo.com

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