The most underrated intervention in medicine, and why most people can no longer have it

Across nine countries and millions of patients, one thing keeps predicting who does well: whether the same person keeps looking at you over time. Here is what the research says, and the question it leaves open for anyone whose care has crossed a border.

There is a medical intervention that costs nothing. It requires no equipment. It has no side effects and is associated with lower mortality in eighteen separate studies across nine health systems.

It’s not sold anywhere. There is no product attached to it. It appears in no wellness protocol and no supplement stack, and I have never seen it recommended on social media. It is continuity. Being looked after, over time, by someone who already knows you.

I want to lay out what the evidence shows, because it is stronger than most people realise. And then I want to put a question on the table that the research has not answered, and that I think about constantly at Strata, because it describes the situation almost every person I work with is in.

What the research found

In 2018, a team at the University of Exeter published the first systematic review examining whether continuity of care with a doctor is associated with mortality. They searched three major databases across twenty-one years, identified 726 candidate articles, and found 22 that met their criteria.

Those studies came from nine countries with substantially different cultures and health systems. The measurement methods varied so much that the results could not be pooled into a single statistic.

Of the 22 studies, 18 reported statistically significant reductions in mortality where continuity of care was higher. Sixteen of those measured all-cause mortality. Three studies found no association, and one produced mixed results. The beneficial effect was seen with both primary care doctors and specialists.

Eighteen out of twenty-two, in nine different countries, with entirely different funding models, referral structures, and cultural expectations of medicine. When a finding survives that much variation, it is unlikely to be an artefact of how one country happens to organise its clinics.

A second review, published in the British Journal of General Practice in 2020, narrowed the question to primary care and looked harder at how strong the association was. Of the twelve studies measuring all-cause mortality, nine found a statistically significant protective effect of greater continuity, two found none, and in one the result shifted from increased to decreased mortality depending on which measure of continuity was used.

Then, in 2023, a Danish team did something the earlier work could not. Rather than sampling, they used national registry data covering every contact with primary care and hospitals in a single year, for 4.7 million adults. Effectively, an entire country.

People who saw their usual doctor for less than 1 out of every 4 visits were about 1.5 times more likely to get a medication they shouldn't have, compared to people who always saw the same doctor. They were also more than 2.5 times as likely to die during the study period.

These figures were adjusted for demographics, socioeconomic factors, and how ill each person was. The pattern held regardless of how many conditions someone had.

The medication finding is the one I would ask you to sit with, because the mechanism is not mysterious. A potentially inappropriate medication is a drug that should not have been given to that person, in that combination, at that time. It is what happens when the person writing the prescription does not have the full picture of what else is already in the body.

Why it might work

The reviewers looked at what the individual studies proposed as explanations, and three ideas pop up.

• Greater physician knowledge of the patient.

• Increased patient trust, which improves adherence to medical advice.

• Enhanced clinical responsibility, meaning a doctor who expects to see you again takes more ownership of what happens next.

Look carefully at the first one. Not better drugs. Not more tests. Not newer technology. The doctor simply knowing more about the person sitting in front of them.

There is supporting evidence for this reading from an unusual source. In the United States veterans and defence health systems, researchers examined what happened when clinicians used an integrated viewer that assembled a patient's records from multiple separate electronic systems into one place. Providers who had used that viewer ordered significantly fewer duplicate imaging studies than those who had not, with an odds ratio of 0.44, a result robust across several statistical models.

Same clinicians. Same patients. Same training. One difference: whether the record had been assembled before the decision was made.

What this does not prove

All of the studies we've talked about so far have one thing in common: they watched what happened to people, but they didn't choose who got continuous care and who didn't. No one has done a study where they randomly put patients into two groups - one that always sees the same doctor and one that doesn't - and then compared the results. That kind of study would be hard to do in a way that's fair to everyone.

The researchers who reviewed these studies brought up some important questions themselves. One study pointed out that patients who are very sick might see whichever doctor can see them fastest, which would make it look like they have less continuity of care. Another study suggested that higher death rates could be because people who are already more seriously ill tend to see more doctors.

In other words, it's possible that seeing lots of different doctors is more a sign of being very sick than it is the cause of worse health. A different review of studies about fragmented care in hospitals said this straight out: because most of the studies looked back at what already happened rather than watching it happen in real time, we can't say for sure whether fragmented care caused the bad outcomes or the other way around.

That objection deserves a serious answer, and there is one.

Researchers at Mathematica set out to explain who ends up with highly fragmented care. They assembled a set of characteristics covering patients, primary care providers, practice sites, and geographic markets. Together, all of it explained about six percent of the variation in whether a person received highly fragmented care.

They also found that fragmentation was not substantially higher among sicker patients, which suggests that medical need is not what drives it.

Ninety-four percent of the variation is something else: how many doors you happened to walk through, whether your doctor retired, whether you moved, whether your specialist referred you onward, whether you changed insurer, whether you changed country.

So fragmentation is not simply a marker of illness. It is largely the result of specific life events. And those events are not distributed based on who is sickest or who needs continuity most.

The problem with the recommendation

If you read the conclusions of these papers, the practical advice is consistent: maintain a relationship with a usual provider, reduce transitions, improve coordination.

It is good advice. It is also, for a large and growing number of people, impossible.

Consider who cannot follow it. Anyone who has emigrated. Anyone treated in a public system where you see whoever is on rotation. Anyone whose long-standing family doctor has retired. Anyone managing several conditions, each of which belongs to a different specialty. Anyone who moved cities for work, or moved countries for family, or lives between two.

Every study measures continuity as a property of a relationship. And relationships of that kind are becoming less available, not more. The research is describing something real and valuable that a significant proportion of the population structurally cannot have.

That is where the literature currently stops. And it is exactly where my work begins.

The open question

Here is what I would want to see studied.

If a meaningful part of the benefit of continuity comes from the doctor knowing more about the patient, as several of these studies propose, then the question is where that knowledge has to live.

Does the knowledge have to live in a relationship with your GP, or can it live in a document the patient carries?

I am not aware of a single study that has taken people with structurally fragmented care, given half of them a properly assembled longitudinal record to bring to every appointment, and measured what happened. What we do have is the adjacent finding: when clinicians in the veterans and defence systems were handed an assembled record, their prescription ordering behaviour changed measurably. That is not the same as proving that patient-facing document reduce mortality, however, it is a reason to think the question is worth asking.

I would also be honest about what a document cannot replace. It cannot supply trust. It cannot create the sense of ownership that comes from a doctor expecting to see you next year. Two of the three proposed mechanisms are relational, and paper does not do relationships.

But the third mechanism, knowledge of the patient, is information. And information can be written down.

Continuity of Care at Stratacr.com

What should you take from this

Three things.

First, continuity is not a soft preference. It is an intervention we can treat as serious medicine, and it is associated with fewer inappropriate prescriptions and lower mortality across nine health systems and millions of people.

Second, most of the fragmentation in your life is not about how sick you are, though 6% is. The rest is circumstance, and circumstance does not ask permission.

Third, if you cannot have a relationship with your GP, the question becomes what else can carry the information. Right now, in most people's lives, the answer is nothing. The information sits in four portals, two countries, one drawer, and a memory that is asked to perform under pressure in a ten minute appointment.

That is the gap I work in. Relationship. Being the voice on the phone that checks in, that asks how you're doing, that catches the thing you forgot to mention last time. Being the person who holds your hand while you implement the changes, who celebrates the victories with you and sits with you through the hard days.

And yes, also assembly. Taking everything that already exists, in whatever language and whatever condition, and stitching it together into a story that lets a clinician see your whole self in the few minutes they have with you. But that assembly is only possible because of the relationship. Because you trusted me with the details nobody else asked for.

The research says the person who knows your history is your most valuable clinical asset.

For a great many people now, that person is going to have to be you. Not alone, but as the curator of your own story. As the keeper of the details that slip through the cracks of a ten-minute appointment. As the constant in a sea of variables.

That is a hard job, and it is an unfair job. It should not fall to the person who is already managing the condition to also manage the record. But here is the thing about hard and unfair jobs: they are so much less hard and so much less unfair when you have someone in your corner.

You should not have to do this alone. And with Strata, you don't have to.

Sources

• Pereira Gray DJ, Sidaway-Lee K, White E, Thorne A, Evans PH. Continuity of care with doctors, a matter of life and death? A systematic review of continuity of care and mortality. BMJ Open, 2018.

• Baker R, Freeman GK, Haggerty JL, Bankart MJ, Nockels KH. Primary medical care continuity and patient mortality: a systematic review. British Journal of General Practice, 2020.

• Healthcare fragmentation, multimorbidity, potentially inappropriate medication, and mortality: a Danish nationwide cohort study. BMC Medicine, 2023.

• Mathematica. Studies on the persistence and predictors of fragmented care, published in Medical Care and Health Services Research.

• Integrated health record viewers and reduction in duplicate medical imaging: retrospective observational analysis. Journal of Medical Internet Research.

• Patient outcomes following interhospital care fragmentation: a systematic review. Journal of General Internal Medicine, 2019.

Strata is an integrative health analysis practice in Costa Rica, working with people whose medical history is spread across multiple providers, systems, and countries. Strata does not diagnose, treat, or prescribe.