Sources and Further Reading
This book is a synthesis for general readers, not original research. Every chapter carries its own "Sources and notes" section naming the specific trials, agencies, and papers behind its claims, plus an "Open questions" note flagging anything genuinely unsettled, disputed, or likely to date quickly. This page covers what recurs across chapters and how to read the numbers.
How to read the numbers in this book
Global figures are modelled estimates, not counts. Roughly half the deaths in the world are never registered with a certified cause. Prevalence and mortality figures for whole populations come from surveys, sample registration, hospital data, verbal autopsy, and statistical models. The two largest producers, the World Health Organization and the Institute for Health Metrics and Evaluation (which runs the Global Burden of Disease study), often publish different numbers for the same quantity because they define and model it differently. Both are competent. Neither is a count.
Read them as accurate in direction and rank order, uncertain in the last digit. When this book says 589 million adults have diabetes, that is the International Diabetes Federation's central estimate for 2024, with a wide interval around it, revised at each edition.
Prevalence changes when definitions change. Part of the apparent rise in hypertension, prediabetes, and osteoporosis is real and part is threshold movement, as Chapter 12 explains.
Survival statistics describe populations diagnosed years ago, under older treatments, across all ages and stages. They tell you about a disease. They do not tell an individual their future.
Effect sizes quoted for treatments come from randomised trials where possible, and trial populations are usually healthier and better monitored than everyone else, so real-world effects are generally smaller.
The organisations that recur
Worth recognising on sight, because they produce most of the figures here.
| Source | What it produces |
|---|---|
| World Health Organization (WHO) | Global health estimates, fact sheets, the annual World health statistics, and disease-specific flagship reports on TB, malaria, hepatitis, and hypertension |
| Global Burden of Disease (IHME) | Cause-specific mortality, incidence, prevalence, and DALYs for every country, published mostly in The Lancet |
| UNAIDS | HIV epidemiology and treatment coverage |
| UNICEF and the UN IGME | Child and neonatal mortality |
| International Diabetes Federation | The IDF Diabetes Atlas, the standard diabetes prevalence source |
| IARC (part of WHO) | GLOBOCAN cancer incidence and mortality estimates, and the Monographs classifying carcinogens |
| US CDC and national equivalents | Surveillance, outbreak reports, and vaccine schedules |
| Cochrane | Systematic reviews synthesising trial evidence |
| NICE (UK), USPSTF (US), and equivalents | Guidelines and screening recommendations, which frequently differ between countries on the same evidence |
Clinical specialty bodies supply the disease-specific standards cited in individual chapters: the American Diabetes Association, GINA and GOLD for asthma and COPD, KDIGO for kidney disease, ACC/AHA and ESC for cardiovascular disease, the International League Against Epilepsy, EULAR and ACR for rheumatology, and others named where used.
Where to go deeper
For general readers
- Siddhartha Mukherjee, The Emperor of All Maladies (cancer) and The Gene
- Randolph Nesse and George Williams, Why We Get Sick, on evolutionary medicine
- Michael Marmot, The Health Gap, on the social gradient
- Ben Goldacre, Bad Science and Bad Pharma, on evidence and its distortions
- Atul Gawande, Being Mortal, on the end of life and the limits of intervention
- Paul Farmer, Infections and Inequalities, on global health and who gets treated
- Rebecca Skloot, The Immortal Life of Henrietta Lacks, on research ethics and consent
- H. Gilbert Welch, Less Medicine, More Health, on overdiagnosis and screening
- Frank Snowden, Epidemics and Society, on how disease shaped history
Reference texts, if you want the primary version
- Harrison's Principles of Internal Medicine and the Oxford Textbook of Medicine
- Robbins, Basic Pathology, for mechanisms
- Janeway's Immunobiology
- Rang and Dale, Pharmacology
- Nussbaum, Thompson & Thompson Genetics in Medicine
- Heymann, Control of Communicable Diseases Manual
Checking something yourself
- PubMed (pubmed.ncbi.nlm.nih.gov) indexes the medical literature. Search the drug or condition plus "randomized" or "systematic review".
- Cochrane Library for pooled evidence on a specific question.
- ClinicalTrials.gov for what is currently being tested, and for whether a trial's published outcomes match its registered ones.
- Our World in Data for accessible, sourced versions of most global health figures in this book.
- National guidelines (NICE, USPSTF, and your own country's) for what is actually recommended where you live, which is frequently more current than any book.
What this book deliberately leaves out
The very rare, the highly specialised, and anything where a short summary would be more dangerous than no summary. Also: specific doses, specific brand recommendations, and anything resembling personalised advice. Chapter 17 is the tool for evaluating claims this book does not cover, and a clinician who can examine you is the tool for everything else.
A final note on certainty
Every chapter here contains claims that will be wrong within a decade. That is not a failure of the book; it is how the field works. The parts most likely to change are the treatment sections, where new drug classes arrive regularly, and the "what's next" sections, which are predictions and should be read as such. The parts least likely to change are the mechanisms: what insulin does, why a plaque ruptures, how an antibody works, why a nerve fires. Those are the reason the book is organised around mechanisms rather than around drug names.
Where the science is genuinely unsettled, each chapter says so directly rather than picking a side. Where a widely repeated claim turns out to be wrong (the chemical imbalance theory of depression, the serotonin story, the belief that ulcers are caused by stress, the idea that back pain requires a scan), the text says that too.