Continuity of care: what lasting bonds change

An older man comes to the appointment saying he "is not well". He has no fever, his blood pressure is within the expected range and the exam shows nothing that draws attention. For someone seeing him for the first time, the appointment ends with general guidance. For the doctor who has followed him for years, there is a detail that does not appear in any number: he always arrives alone and in a good mood, and today he came accompanied by his daughter, silent. She orders tests the same day and schedules a return visit for the following morning.

This difference has a name in the primary care literature: longitudinality, the relationship between a person and a professional or team that is maintained over time. This text explains the concept, shows how it is measured, summarizes what the reviews found about mortality, hospitalization and costs, discusses why the bond seems to work and points out the risk it brings to clinical reasoning.

Key points

• Longitudinality is the relationship with the same professional or team over time; it is not to be confused with the number of appointments.
• The literature describes three types of continuity: informational, management and relational.
• Systematic reviews associate greater continuity with lower mortality, with evidence that is mostly observational.
• Registry and administrative database studies associate continuity with fewer acute hospitalizations, less use of emergency services and lower spending.
• The bond seems to act through accumulated knowledge, trust and clinical responsibility, mechanisms that have still been little tested directly.
• Knowing the patient helps to notice small changes, but it can anchor reasoning in old explanations.
• Protecting continuity depends on service organization, well-kept records and planned reassessment.

Summary

• What longitudinality is
• The three types of continuity
• How continuity is measured
• What the evidence shows about mortality
• Hospitalization, emergency care and costs
• Why the bond works
• The risk of the bond: anchoring and the accustomed eye
• How to protect continuity in practice
• Frequently asked questions
• Final checklist

What longitudinality is

The multidisciplinary review by Haggerty and colleagues looked for what the different health fields understand by continuity and found two elements that distinguish it from other attributes: care for an individual patient and care offered over time (Haggerty, 2003). Both need to be present. A service that cares well for a population but never sees the same person twice has no continuity; an excellent, isolated appointment does not either.

In primary care, longitudinality is the name given to this extended relationship. It presupposes that the person recognizes a professional or team as their reference and that this professional or team takes responsibility for their care for years, and not only during an episode of illness. The relationship includes the periods when the person is well, because that is where the knowledge that will be used when they fall ill is built.

A consensus study with experts developed operational definitions for 25 attributes of primary care and concluded that only five are specific to this level of care, among them relational continuity (Haggerty, 2007). Attributes such as technical quality and communication matter in any setting. A stable relationship over time, by contrast, is a mark of primary care.

In a systematic review of the dimensions that make up a primary care system, continuity appears as one of the four dimensions of the care process, alongside access, coordination and comprehensiveness (Kringos, 2010). It does not work alone. A lasting bond with a service that solves little or that loses information along the way delivers less than it promises.

The three types of continuity

Haggerty and colleagues proposed separating continuity into three types, which answer different questions (Haggerty, 2003). Informational continuity is the use of information about past events and personal circumstances to make current care appropriate to the person. Management continuity is a coherent and consistent approach to a health problem, which responds to changes in the patient's needs. Relational continuity is an ongoing therapeutic relationship between the patient and one or more professionals.

The three types support each other, but they can exist separately. A complete medical record allows informational continuity even when the professional changes. A protocol that is well followed between services allows management continuity without the patient knowing who is treating them. Relational continuity is the one that comes closest to longitudinality and the one that depends most on time.

Type of continuity	What it is	How it appears in practice	Sign that it is failing
Informational	Use of the person's history and circumstances in current care	The professional checks previous records and context before deciding	Repeated tests, forgotten allergies and important events
Management	Coherent approach to a problem over time and between services	Shared plan, revised goals, same logic of follow-up	Contradictory decisions between visits or between services
Relational	Continuous therapeutic relationship with one or more professionals	The patient knows who to turn to and the professional knows their baseline	Each visit starts from scratch, with someone else

The written record is the link between the three types. A note that explains the reasoning, and not just lists findings, allows another professional to continue the care when the relationship is interrupted, as discussed in the text about long notes, copying and ready-made templates in the medical record.

How continuity is measured

Measuring a relationship is difficult, and most studies measure what is easiest to record: the pattern of visits. Haggerty and colleagues observed that many measures focus on the chronological sequence of appointments without directly measuring the continuity experienced by the patient (Haggerty, 2003). The number says who provided care, but it does not say whether there was knowledge, trust or responsibility.

The most used indices answer slightly different questions. The proportion of visits with the most frequent professional shows how much of the care is concentrated in one person. Indices of dispersion among professionals penalize care spread across many different people. The duration of the relationship with a named professional measures how long the bond has existed. And patient experience questionnaires try to capture whether the person feels known and followed.

A study of more than 1.4 million older beneficiaries seen by 6,551 primary care physicians calculated four of these indices and found a very high correlation between them, with coefficients between 0.86 and 0.99 (Bazemore, 2018). For comparing services, the choice of index seems to matter little. For understanding what happens within the relationship, all of them are limited.

The duration of the bond is the measure closest to the idea of longitudinality. A national registry study used the duration of the relationship between the person and their reference physician, categorized from one year to more than 15 years, as a measure of continuity (Sandvik, 2022). This approach has a practical advantage: the data already exists in systems with a list of patients per professional and does not require counting visits.

What the evidence shows about mortality

The first systematic review on continuity and mortality identified 726 articles and included 22 studies, cohort or cross-sectional, from nine countries with very different cultures and health systems (Pereira Gray, 2018). The heterogeneity of the measures prevented meta-analysis. Still, 18 of the 22 studies showed a significant reduction in mortality with greater continuity, 16 of them with all-cause mortality (Pereira Gray, 2018).

The same work found three studies with no association and one with a mixed result, and observed the protective effect with both general practitioners and specialists (Pereira Gray, 2018). The authors stress that all the evidence is observational. This does not reduce the consistency of the finding, but it limits what can be said about cause.

A second review, restricted to primary care, included 13 quantitative observational studies (Baker, 2020). Twelve measured all-cause mortality: nine found a significant protective effect of greater continuity, two found no effect, and one had results that varied depending on the continuity measure used (Baker, 2020). The remaining study found a protective association for mortality from coronary disease.

The authors of that review make two important caveats. No study directly investigated the mechanisms, and reverse causality remains possible, that is, people at higher risk of dying may be less likely to see the same professional, for example because of hospital admissions or frequent moves (Baker, 2020). They also suggest that the simple idea that "continuity is good for everyone" may hide a large benefit for many and a disadvantage for a few (Baker, 2020).

Reading these studies requires remembering the pitfalls of observational designs, such as confounding and reverse causality, reviewed in the text on study designs and their weaknesses. Clinical trials that randomize people to have or not have a reference professional are hard to run, and may never exist on a large scale. The strength of the evidence comes from the finding being repeated in very different contexts.

Hospital admission, emergency care and costs

Mortality is the strongest outcome, but not the only one. An older critical review gathered 40 studies on interpersonal continuity and care outcomes, with 81 outcomes analyzed: 51 improved significantly with greater continuity and only two worsened (Saultz, 2005). In the same review, 20 studies on costs showed lower cost or lower service use in 35 of 41 variables associated with continuity (Saultz, 2005).

The authors of that review acknowledge persistent methodological problems in the literature, such as heterogeneous measures of continuity and designs that do not allow inferring cause (Saultz, 2005). The pattern, however, points in a single direction: almost no study found worsening associated with continuity.

The national registry study with more than four million people listed with a reference physician is one of the broadest on the topic (Sandvik, 2022). Compared with a one-year relationship, the chance of using out-of-hours emergency services fell gradually to an odds ratio of 0.70 after more than 15 years of relationship (Sandvik, 2022). The chance of acute admission fell to 0.72 and the chance of dying in the year studied fell to 0.75 with more than 15 years of relationship (Sandvik, 2022).

The authors highlight the gradient: the longer the relationship, the lower the chance of each outcome, which reinforces the plausibility of a causal relationship (Sandvik, 2022). The design remains observational, and a gradient can also arise if healthier people tend to keep the same physician for longer.

The study with older beneficiaries reached a similar result by another route. Patients seen by physicians in the highest continuity quintile had significantly lower total spending and chance of admission than those seen by physicians in the lowest continuity quintile, and this held for all four indices tested (Bazemore, 2018). The authors suggest that these indices could serve as measures of quality and of resource use.

Why the relationship works

None of the reviews directly tested the mechanisms, but the authors propose explanations consistent with what is known about the consultation. The review on primary care lists greater clinical responsibility, greater physician knowledge of the patient and greater patient trust as mechanisms suggested by the studies, not yet investigated (Baker, 2020). The other review adds greater adherence to preventive measures and to treatments, and the patient's perception that the physician has become more responsive, which leads the person to disclose more (Pereira Gray, 2018).

A synthesis of qualitative studies on the patient perspective helps organize these ideas. From 11 studies in four countries, the authors identified longitudinal care and consultation experiences as the two processes that promote the relationship, and described the depth of the relationship in four elements (Ridd, 2009):

• Knowledge: what the professional knows about the person and what the person knows about the professional.
• Trust: the expectation that the other person will act in the patient's interest.
• Loyalty: the willingness to return to the same professional and to keep them as a reference.
• Regard: the feeling of being treated as a person, and not only as a problem.

Trust does not need years to exist, but it changes in nature over time. In interviews with 20 patients, trust in an unfamiliar doctor rested on expectations about medicine as an institution and about doctors as professionals (Tarrant, 2010). Repeated interactions with the same doctor allowed safer expectations, based on the history of previous encounters and on the anticipation of future encounters (Tarrant, 2010).

For clinical reasoning, the most concrete mechanism is the baseline. Someone who follows a person knows their usual values, their way of reporting symptoms and what tends to be normal for them. A vague complaint gains meaning when it is compared with the person's own pattern, and not with the population average. Much of the diagnosis comes from the history, as the text on how much of the diagnosis comes from the history shows, and the history becomes richer when there is trust to tell it.

Accumulated knowledge also changes what the patient reveals. People who feel known tend to bring up concerns they would not bring to a stranger, and these clues often appear in the middle of the consultation, as the text on clues the patient offers discusses. Narrative medicine goes in the same direction by treating the history as clinical data, as the text on why the history matters for diagnosis shows.

The risk of the bond: anchoring and the accustomed gaze

Accumulated knowledge has a cognitive cost. Someone who knows a patient well tends to explain each new symptom through the diagnoses they already know. The fatigue complaint of a person with long-standing depression is attributed to depression; the chest pain of someone with anxiety is attributed to anxiety. This is the clinical form of anchoring: reasoning stays stuck to the first available explanation.

A systematic review on cognitive biases in medical decisions included 20 studies with 6,810 doctors and found overconfidence, anchoring effect and information and availability biases associated with diagnostic inaccuracies (Saposnik, 2016). The authors note that 12 of the 20 studies were classified as low quality and that more complete studies are lacking (Saposnik, 2016). The review did not specifically study known patients, but it describes the mechanism that familiarity can amplify.

The continuity literature acknowledges this side. The review on mortality in primary care recalls that the benefit for many may come with disadvantage for some (Baker, 2020). The authors of the other review suggest that doctors tend to overestimate their effectiveness with patients they do not know and to underestimate it with those they do know (Pereira Gray, 2018). Neither statement removes the need to watch for the risk of always seeing the same picture.

Some signs suggest that familiarity may be getting in the way. The new symptom is explained by an old diagnosis without a targeted examination, or the complaint repeats across several consultations and the explanation never changes. The professional feels they "already know" what the patient will say before listening. There is a label in the record, such as "frequent complainer" or "anxious", that precedes any assessment. Or the emotion toward the patient, sympathy or irritation, influences the decision to investigate.

These mechanisms have names and have already been discussed in other texts. Anchoring and availability are useful heuristics that become traps under certain conditions, as the text on when the heuristic helps and when it gets in the way shows. Affection for the patient can reduce the willingness to investigate, the theme of the text on what affective bias is. And written labels tend to perpetuate themselves from consultation to consultation, as the text on the record as amplifier discusses.

The answer is not to give up the bond, but to use it methodically. Asking "what changed?" before "what do I already know?", examining again when the complaint changes character and accepting a second opinion from a colleague are ways to keep a fresh eye without losing accumulated knowledge. Checking from time to time whether confidence in your own diagnosis matches your accuracy also helps, as the text on what diagnostic calibration is explains.

How to protect continuity in practice

Continuity does not depend only on the professional's will. It is produced or destroyed by how the service is organized. A review of the dimensions of primary care gathered evidence that consultation length influences continuity through the quality of the clinical record and patient enablement (Kringos, 2010). Consultations that are too short weaken the record, and a poor record weakens informational continuity when the professional changes.

There is a real tension between quick access and continuity. Services that prioritize seeing anyone the same day, with whoever is available, tend to fragment the relationship. The authors of the study on trust observe that many services focus increasingly on expanding access rather than continuity, and warn about the effect of this on trust (Tarrant, 2010). The review on mortality in primary care adds that relational continuity is declining in some countries, despite the evidence of benefit (Baker, 2020).

Not every patient needs continuity to the same degree. The review on mortality in primary care observes that young, healthy people may not want or need to see the same doctor, while older people with several chronic conditions often do (Baker, 2020). Prioritizing continuity for those who benefit most is a way to reconcile access and bond.

Practical measures that protect continuity:

• A list of patients by professional or by small team, so that each person knows who their reference is.
• A schedule that reserves slots for follow-ups with the same professional, especially for people with chronic diseases and multimorbidity.
• A record that explains the reasoning and the plan, not just the findings, so that another professional can continue.
• An explicit handover of care when the reference professional leaves, with a conversation and a transition note.
• A planned follow-up, with a date and a criterion, when the diagnosis is not yet settled.

The last point links continuity to uncertainty. When the picture is not defined at the first consultation, scheduling the reassessment with the same professional allows comparing the evolution with what was seen before, a strategy described in the text on planned reassessment. The bond gives time diagnostic value, because whoever saw the patient yesterday notices better what changed today.

Frequently asked questions

Is longitudinality the same as continuity?

In practice the terms overlap. Haggerty's review describes three types of continuity, informational, management and relational, and longitudinality corresponds mainly to relational continuity, the therapeutic relationship with one or more professionals over time (Haggerty, 2003).

Does continuity really reduce mortality?

Systematic reviews find a consistent association between greater continuity and lower mortality in studies from many countries (Pereira Gray, 2018). All this evidence is observational, and reverse causality cannot be ruled out (Baker, 2020). The finding is consistent, not definitive.

How is continuity measured in a service?

The most used indices count the concentration of consultations with the same professional or the duration of the bond. Different indices tend to give very similar results when applied to the same data (Bazemore, 2018). None of them directly measures the quality of the relationship.

Does continuity apply to the team as well, or only to the doctor?

The definition of relational continuity includes the relationship with one or more professionals (Haggerty, 2003). A small, stable team, with a shared record and meetings about patients, can offer part of the benefits. Most studies, however, measured continuity with doctors.

Can knowing the patient for years get in the way of the diagnosis?

It can. Familiarity encourages anchoring to old diagnoses, and anchoring is among the biases associated with diagnostic inaccuracy (Saposnik, 2016). Asking what has changed, examining again and asking a colleague's opinion reduce the risk.

Does this text guide individual conduct?

No. It presents one attribute of primary care and the evidence about it, and it does not replace the clinical assessment of each patient.

Final checklist

• Ask the patient who their reference professional or team is and for how long.
• Record the person's baseline: usual values, functionality and way of reporting symptoms.
• Write the reasoning and the plan in the medical record, not just the findings.
• When faced with a new complaint, first ask what has changed relative to the person's pattern.
• Re-examine when the complaint changes character, even if an old explanation exists.
• Be wary of labels in the medical record that precede any assessment.
• Schedule a follow-up with the same professional when the diagnosis is not settled.
• When leaving the service or handing over care, write a clear transition note.

References

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