Community Medicine — Injury Prevention, NMC MBBS licence examination syllabus (Nepal Medical Council).
Injury Prevention: the word "accident" is doing real harm
Injuries happen on the same roads, at the same hours, to the same age groups, in the same way. That is not what luck looks like.
A young man on a motorcycle, no helmet, evening, a road with no separation between fast and slow traffic. He arrives in the emergency department with a head injury, and everything that follows is superb: resuscitation, imaging, neurosurgery, intensive care.
He still dies. And the same case arrives next week.
Clinical medicine engages with injury only at the last possible moment, when the energy has already been delivered to the body. Almost everything that decides the outcome happened before the patient reached you — and those things are the subject of this chapter.
Why the word matters
"Accident" means bad luck: an event nobody could have foreseen or prevented. That framing has a practical consequence — a thing that cannot be prevented does not get a budget, a policy, or a programme. It gets sympathy.
But injuries are not randomly distributed. They cluster on particular roads, at particular hours, in particular age groups, with the same contributing factors appearing again and again. Anything that predictable can be studied epidemiologically like any other disease — and anything that can be studied can be reduced.
This is why the field is called injury prevention, and why professional writing avoids "accident" entirely.
One more reason injury deserves attention out of proportion to its death count: it kills the young. A disease that kills at seventy-five removes a few years of life; an injury that kills at twenty removes fifty. Measured in years of life lost, injury outranks many conditions that receive far more clinical attention.
Haddon's matrix: three chances, not one
Haddon's insight was to split an injury event into three phases and ask what could be changed in each. Take the motorcyclist:
Before the crash — everything that determines whether the crash occurs at all: road design, speed, alcohol, licensing, vehicle condition, visibility.
During the crash — everything that determines how much energy reaches the body: a helmet, a seatbelt, a crash barrier rather than a concrete pole, a child restraint.
After the crash — everything that determines what the injury costs: bystander first aid, how quickly an ambulance arrives, whether the receiving hospital can manage trauma, and rehabilitation.
The point of the matrix for a clinician is uncomfortable but important: we work almost exclusively in the third column, which is where the least benefit is available. The helmet that was not worn mattered more than anything the neurosurgeon can do afterwards.
The matrix is also a reliable exam structure. Asked how to reduce injury from any cause — road, burns, drowning, occupational — answer in three phases and you will produce a complete answer without memorising a list.
Passive protection beats good intentions
Interventions divide into two kinds, and they do not perform equally.
Active protection requires the individual to do something correctly, every single time: remember the helmet, fasten the belt, lock the cupboard, watch the child. It depends on attention, motivation and memory — which fail when people are tired, rushed, drunk, or simply distracted, and those are exactly the circumstances in which injuries occur.
Passive protection works whether anyone remembers or not, because it is built into the environment: a divided carriageway, a speed hump, a child-resistant container, a fenced well, a guarded machine.
Why does this distinction matter for the exam? Because it predicts which programmes succeed. Education campaigns alone reliably underperform, and asking why produces the answer: they demand sustained individual effort from everyone, forever. Engineering and legislation demand it once, from a designer or a legislator.
This is the same principle met in salt iodisation and clean water supply. The best public health interventions ask nothing of the individual.
Road traffic injury
Who actually dies is the first thing to get right. In many low- and middle-income settings the majority of road deaths are not car occupants — they are pedestrians, motorcyclists and cyclists, people outside a protective shell. A road system designed around vehicle flow while ignoring these users produces exactly the injuries seen.
Four factors are modifiable, and they carry most of the benefit:
Speed. The master variable. It determines whether a collision can be avoided at all, and how much kinetic energy is transferred if it cannot. Small reductions in speed produce disproportionate reductions in death — because energy rises with the square of velocity.
Alcohol. Impairs judgement, reaction time and coordination simultaneously.
Helmets. The single most effective intervention for motorcyclists, acting in the "during" column by reducing energy transmitted to the skull and brain.
Seatbelts and child restraints. Same principle for vehicle occupants.
And one systems point that examiners like: a law without enforcement changes behaviour very little. Helmet legislation raises helmet use where it is enforced and visibly so; where enforcement is absent, compliance decays quickly. When asked to propose a legislative intervention, always say how it will be enforced — that is what turns a plausible answer into a complete one.
Injury in the home, and the child
Childhood injury is not random either — it tracks developmental stage, because what a child can physically do determines how they can be hurt.
An infant who can roll can fall from a bed or a surface.
A crawling infant who mouths everything can be poisoned or can choke.
A walking toddler can reach a cooking fire, a bucket of water, or a hot pot.
An older child ranges further and is exposed to roads and to water.
Burns and scalds are strongly shaped by how a household cooks. Cooking at floor level over an open flame places the fire and the pot precisely at a toddler's height and reach, which is why burn patterns differ so much between settings.
Drowning deserves emphasis because it is misunderstood. It is silent and fast — there is usually no shouting or splashing, and a small child can drown in very shallow water in the time it takes to answer a door. Buckets, water tanks, irrigation channels and unfenced wells are the hazards, and the intervention is a barrier, not vigilance.
Poisoning in the home has one recurring, entirely preventable pattern worth stating explicitly: decanting kerosene or paraffin into a used drinks bottle. The child recognises the bottle, not the contents. Store medicines and chemicals out of reach, in their original containers.
Violence and self-harm belong here too
Injury prevention includes intentional injury, which is often separated out and then neglected. Interpersonal violence, gender-based violence and self-harm are all injury, and all follow patterns rather than occurring at random.
One general principle applies across them and is worth knowing: restricting access to the means of injury reduces deaths. Where a particular method is common and available, limiting access to it lowers mortality, because many acts of self-harm are impulsive and the impulse passes. The clinical assessment of self-harm risk is covered in the psychiatric emergencies chapter; the preventive point is that availability is itself a modifiable factor.
Putting it together
Injuries are predictable, therefore preventable. "Accident" is the wrong word because it removes the possibility of action.
Haddon's matrix gives three chances — before, during, after. Clinicians work in the third and least effective one.
Passive protection beats education, because it does not depend on anyone remembering.
Speed, alcohol, helmets and restraints carry most of the road-injury benefit — and a law without enforcement achieves little.
Childhood injury follows developmental stage; drowning is silent, and kerosene in a drinks bottle is a recurring preventable poisoning.
No injury statistics, speed limits or legal alcohol limits are quoted here: rates change with each survey and legal values differ between countries. Take them from your current national source.
Syllabus points
Why injuries are not accidents
Haddon's matrix — before, during, after
Passive vs active protection
Vulnerable road users and the four modifiable factors
Speed as the master variable
Law without enforcement
Childhood injury by developmental stage
Drowning, burns and household poisoning
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