Reading signs and symptoms: the value of history

In a classic study with 80 new patients at a general internal medicine outpatient clinic, the referral letter and the history were enough to reach the final diagnosis in 66 of them (Hampton et al., 1975). The physical exam was useful in 7 patients, and lab tests in another 7 (Hampton et al., 1975). What the patient reports remains the main source of the diagnosis, and knowing how to interpret signs and symptoms is what separates a list of complaints from a hypothesis.

NEXO is a daily medical diagnosis game: one clinical case a day, six progressive clues, and ICD-10 proximity feedback across five levels.

This text deals with the diagnostic value of the medical history and the clinical exam: how much of the diagnosis comes from the history, what the JAMA Rational Clinical Examination series shows about specific findings, why an absent finding also informs, and why two examiners do not always find the same sign. At the end, it proposes a way to read each finding. The calculation of probability before and after a new piece of data is in the text about pre-test probability.

Key points

• In two outpatient studies, the history led to the diagnosis in most patients (Hampton et al., 1975; Peterson et al., 1992).
• The physical exam and additional tests led to fewer diagnoses, but helped rule out hypotheses and increase confidence (Peterson et al., 1992).
• The Rational Clinical Examination series treats each finding from the history and the exam as a test, with sensitivity, specificity and likelihood ratio.
• Some findings weigh heavily when present; others weigh more when absent.
• Different examiners agree little on several signs of the chest exam (Spiteri et al., 1988).

Summary

• How much of the diagnosis comes from the history
• The finding as a test: the Rational Clinical Examination series
• Present or absent
• Agreement between examiners
• How to read a finding
• Where NEXO comes in
• Frequently asked questions
• Checklist for interpreting signs and symptoms

How much of the diagnosis comes from the history

The question "how much of the diagnosis comes from the history?" was tested directly in general internal medicine outpatient clinics, asking doctors to record the diagnosis at different points in the visit.

The Hampton study

Hampton and colleagues asked doctors to record the diagnosis after reading the referral letter and taking the history, then again after the physical exam; these diagnoses were compared with the diagnosis accepted two months after the first visit (Hampton et al., 1975). In 66 of 80 patients, the diagnosis made after the history matched the final one (Hampton et al., 1975). Among the 6 patients in whom the doctor had no diagnosis after the history and the exam, lab tests led to the diagnosis in only 1 (Hampton et al., 1975).

The Peterson study

Peterson and colleagues repeated the idea with 80 outpatients with new or still undiagnosed conditions (Peterson et al., 1992). The history led to the final diagnosis in 61 patients, or 76%; the physical exam in 10, or 12%; and lab investigation in 9, or 11% (Peterson et al., 1992).

Doctors' confidence in the correct diagnosis rose from 7.1 after the history to 8.2 after the physical exam and 9.3 after the tests, on a scale of 1 to 10 (Peterson et al., 1992). The authors note that the physical exam and lab tests led to fewer diagnoses, but were important for ruling out hypotheses and increasing confidence (Peterson et al., 1992).

Study	Patients	Diagnosis from the history	From the physical exam	From the tests
Hampton, 1975	80 (Hampton et al., 1975)	66 (Hampton et al., 1975)	7 (Hampton et al., 1975)	7 (Hampton et al., 1975)
Peterson, 1992	80 (Peterson et al., 1992)	61 (Peterson et al., 1992)	10 (Peterson et al., 1992)	9 (Peterson et al., 1992)

What these numbers say and what they do not say

Both studies are from general internal medicine outpatient clinics, with patients who arrived referred or with new conditions. In other settings, such as the emergency department or surgery, the proportion may be different. As an editorial reading, the message for those studying is the order of priority: a good history comes before the physical exam, and the physical exam comes before ordering tests. Training in the interview and in the exam by parts is in the text about simulation of care.

The finding as a test: the Rational Clinical Examination series

In 1992, JAMA published an article by Sackett on the precision and accuracy of the clinical examination, which opened the series The Rational Clinical Examination (Sackett, 1992). Each article in the series gathers the studies on a clinical question, such as "does this patient have pneumonia?", and calculates how much each finding from the history and the examination helps to answer it.

The language of the series

The articles in the series describe each finding with sensitivity, specificity and likelihood ratio. The likelihood ratio says how much the presence or absence of a finding changes the probability of the disease; the strength of each value and the full calculation are in the section on strength of a likelihood ratio, and a shortcut to do it in your head is in the 15, 30 and 45 rule. Here, the focus is on published examples.

An example: shortness of breath in the emergency department

A review in the series gathered 22 studies on findings that separate heart failure from other causes of shortness of breath in adults in the emergency department (Wang et al., 2005). The physical examination finding that most increased the probability was the third heart sound, with a positive likelihood ratio of 11 (Wang et al., 2005). In the history, the best was a history of heart failure, with a ratio of 5.8, and among the symptoms, paroxysmal nocturnal dyspnea, with a ratio of 2.6 (Wang et al., 2005).

The review also assessed simple tests that are part of the initial evaluation (Wang et al., 2005). Pulmonary venous congestion on chest X-ray had a positive ratio of 12, and atrial fibrillation on the electrocardiogram, of 3.8 (Wang et al., 2005).

Type of data	Finding that most increased the probability	Positive likelihood ratio
History	History of heart failure (Wang et al., 2005)	5.8 (Wang et al., 2005)
Symptom	Paroxysmal nocturnal dyspnea (Wang et al., 2005)	2.6 (Wang et al., 2005)
Sign	Third heart sound (Wang et al., 2005)	11 (Wang et al., 2005)
Chest X-ray	Pulmonary venous congestion (Wang et al., 2005)	12 (Wang et al., 2005)
Electrocardiogram	Atrial fibrillation (Wang et al., 2005)	3.8 (Wang et al., 2005)

Values from the summary by Wang and colleagues (2005), for adults with shortness of breath in the emergency department; they do not apply to other settings.

What the example teaches

The same diagnosis has findings of very different weight. In the review, a symptom such as paroxysmal nocturnal dyspnea increased the probability little, and a sign such as the third heart sound increased it a lot (Wang et al., 2005). For those who study, the lesson is to ask how much each finding weighs, and not only whether it "matches" the disease.

Present or absent

The series shows that some findings help more when they are absent. The general reasoning about the absence of a finding is in the text on differential diagnosis; here, three published examples.

Meningitis in adults

In the review on acute meningitis in adults, which excluded studies with a predominance of children or of immunosuppressed patients, the isolated items of the history had low accuracy: the combined sensitivity was 50% for headache and 30% for nausea or vomiting (Attia et al., 1999). In the physical examination, the absence of fever, of neck stiffness and of altered mental status practically ruled out the diagnosis, with sensitivity of 99% to 100% for the presence of at least one of the three (Attia et al., 1999).

The authors point out that, given the severity of the infection, doctors often need to go straight to lumbar puncture in high-risk patients (Attia et al., 1999). That is, the clinical examination helps to rule out in those at low risk, and the decision in high-risk cases follows another path.

Heart failure in shortness of breath

In the review by Wang and colleagues, the findings that most decreased the probability of heart failure were the absence of a history of the disease, with a negative ratio of 0.45, the absence of dyspnea on exertion, with 0.48, and the absence of crackles, with 0.51 (Wang et al., 2005). An X-ray without cardiomegaly had a negative ratio of 0.33 (Wang et al., 2005).

Community-acquired pneumonia

The review of the series on pneumonia concluded that no single clinical finding, nor any combination of findings, confirms the diagnosis in a patient with suspected pneumonia (Metlay et al., 1997). On the other hand, the absence of any change in vital signs or lung auscultation greatly reduced the probability of pneumonia in some studies (Metlay et al., 1997).

The pattern that repeats

As an editorial reading, the three examples show the same pattern: findings that are frequent in the disease help rule it out when they are absent, and more specific findings help confirm it when they are present. Therefore, a good clinical record also notes the relevant negatives, as suggested by the text on summarizing the problem.

Agreement between examiners

A finding only helps if it is found reliably. Two examiners can auscultate the same patient and describe different signs.

Four examiners, the same chest

In a study with 24 physicians divided into six groups of four, each group examined four patients with well-defined chest signs (Spiteri et al., 1988). The four physicians in a group fully agreed on the presence or absence of the signs only 55% of the time (Spiteri et al., 1988). Wheezes were detected more reliably than other signs, such as whispered pectoriloquy (Spiteri et al., 1988).

Compared with the diagnosis confirmed by tests, 28% of the diagnoses based on clinical findings were wrong, and the more an examiner disagreed with the majority about the signs, the greater the chance of getting the diagnosis wrong (Spiteri et al., 1988). The authors suggest that a list of chest signs ordered by reliability would improve teaching (Spiteri et al., 1988).

Pneumonia and auscultation

In a study with 52 men seen with cough and a change in sputum in an emergency department of a veterans hospital in the United States, three physicians examined the lungs without knowing the history or the X-ray (Wipf et al., 1999). Agreement between them was relatively high, with a kappa, a statistical measure of agreement between examiners, of about 0.5, for crackles in the lateral decubitus position and for wheezes (Wipf et al., 1999).

The clinical diagnosis of pneumonia made by the three had a sensitivity of 47% to 69% and a specificity of 58% to 75%, against the X-ray read by a radiologist (Wipf et al., 1999). The authors conclude that the traditional chest examination, on its own, is not accurate enough to confirm or rule out pneumonia (Wipf et al., 1999).

What to do with this variation

As a practical suggestion, when a finding is decisive for your hypothesis, ask a colleague or the preceptor to confirm it, and describe what you saw or heard, not just the name of the sign.

How to read a finding

Faced with a sign or symptom, the student can always ask the same questions. The list below is a practical suggestion from the Editorial, based on the studies in this text.

Five questions for each finding

1. Which hypothesis does it count for? A finding only has weight in relation to a disease; the same fever weighs differently in each hypothesis.
2. Does it weigh more when present or absent? Findings that are very frequent in the disease help rule it out when they are missing; specific findings help confirm it when they appear.
3. How much does it weigh? If there is a Rational Clinical Examination series review on the question, look for the likelihood ratio.
4. Is it reliable? Signs with low agreement between examiners require confirmation.
5. Does it fit with the rest? An isolated finding rarely decides; what decides is the whole set, organized in the problem summary.

Situation	Possible reading (Editorial suggestion)
Finding common in the disease, absent	It may help rule out the hypothesis
Specific finding, present	It may help confirm the hypothesis
Sign with low agreement	Confirm with another examiner or another data point
Finding that does not fit with the rest	Review the hypothesis or the finding itself

Practice with the history

As a practical suggestion, after taking a history during the rotation, write your main hypothesis before examining the patient and note whether the physical exam confirmed, changed or did not change the hypothesis. It is a personal version of the design of the Hampton and Peterson studies (Hampton et al., 1975; Peterson et al., 1992). The qualifiers that make the history more precise, such as onset, duration and evolution, are in the section on semantic qualifiers.

Studying with the reviews in the series

As a practical suggestion, when studying a complaint, look for an article in the Rational Clinical Examination series about it. Read the summary and note, for each finding, whether it helps more when present or absent. That note is worth more than memorizing the list of signs of the disease, because it shows the weight of each one.

Common mistakes when reading a finding

The mistakes below are a practical suggestion from the Editorial, linked to the studies in this text:

• Adding findings as if they all weighed the same: in the review on shortness of breath in the emergency department, findings for the same diagnosis had very different likelihood ratios (Wang et al., 2005).
• Looking only at what is present: in adult meningitis, what helped most to rule out the diagnosis was the absence of three exam findings (Attia et al., 1999).
• Trusting a sign without checking: in the study of chest examination, those who disagreed most with the majority about the signs made more diagnostic errors (Spiteri et al., 1988).
• Skipping the history to get to tests quickly: in outpatient studies, the history led to most diagnoses (Hampton et al., 1975; Peterson et al., 1992).
• Reading the sign outside the setting: the values from a review apply to the population studied, such as adults with shortness of breath in the emergency department, and not to any patient.

Recording the finding in a useful way

As a practical suggestion, when recording a finding, note three things: what you saw, heard or the patient reported, in the most concrete words possible; whether it was confirmed by another person or another piece of data; and which hypothesis it counts for. That record helps in the presentation to the preceptor and in reviewing the case later. A finding described clearly also allows another examiner to look for it in the same way, which connects with the difficulty in agreement shown by Spiteri and colleagues (Spiteri et al., 1988).

Where NEXO comes in

In a case with clues, each clue is a finding from the history, the exam or a complementary test, and the task is exactly that of this text: deciding how much each one weighs. NEXO presents each case in up to six clues, one at a time, and each guess shows the proximity in ICD-10.

Reading the clues as findings

The Daily mode brings one case per day, the same for everyone, and the Archive gathers previous cases. As a practical suggestion, for each clue ask which hypothesis it counts for and whether it weighs more when present or absent; at the end, compare with the explanation of the case. The practice of updating the list with each clue is in the text on differential diagnosis.

Image, tracing and sound

Multimedia brings cases with image, audio and other tests as clues: an electrocardiogram, a chest X-ray or an auscultation sound. It is a good place to practice describing the finding before the name, as suggested in the section on agreement between examiners. The sequence, the ranking and the achievements follow consistency, and the Anki button leads to a card for the finding that was missing, as described in the guide on spaced repetition.

To research, bring to the class and create

If you research the diagnostic value of the clinical exam and want to propose studies with NEXO, check out NEXO Researcher. To bring NEXO to medical school, the student league or residency, there is NEXO Closer. Physicians who review cases in their specialty take part through NEXO Curator, and those who create health content on social media can take part through NEXO Creators.

Frequently asked questions

How much of the diagnosis comes from the clinical history?

In two studies in a general internal medicine outpatient clinic, the history led to the diagnosis in most patients: in 66 of 80 in one study (Hampton et al., 1975) and in 76% in the other (Peterson et al., 1992). In other settings the proportion may be different.

What is the physical exam for if the history does most of the work?

In Peterson's study, the physical examination and tests led to fewer diagnoses, but they helped rule out hypotheses and increased confidence in the correct diagnosis (Peterson et al., 1992). Some signs also weigh heavily, as the reviews in the Rational Clinical Examination series show.

What is the Rational Clinical Examination series?

It is a JAMA series, opened in 1992 by a Sackett article on the precision and accuracy of the clinical examination (Sackett, 1992). Each article answers a clinical question and shows how much each finding from the history and the examination helps to answer it.

Does an absent finding help with the diagnosis?

It helps, especially when the finding is common in the disease. In adult meningitis, the absence of fever, neck stiffness and altered mental status practically ruled out the diagnosis in the review by Attia and colleagues (Attia et al., 1999).

Why do two doctors hear different things in the same patient?

Many signs have low agreement between examiners. In Spiteri's study, four doctors agreed completely on chest signs only 55% of the time (Spiteri et al., 1988). Wheezes were more reliable than other signs.

Is the clinical examination enough to diagnose pneumonia?

In the series review, no single finding or combination confirmed pneumonia, although normal vital signs and auscultation greatly reduced the probability in some studies (Metlay et al., 1997). The approach in each case depends on the assessment of the doctor in charge.

How do you know how much a finding weighs?

Look for a review on the clinical question, such as those in the Rational Clinical Examination series, and check the likelihood ratio of the finding. In the review by Wang and colleagues, for example, the third heart sound had a positive likelihood ratio of 11 for heart failure in adults with shortness of breath in the emergency department (Wang et al., 2005). The full calculation is in the text on pretest probability.

How does NEXO help interpret signs and symptoms?

Each case arrives with up to six clues, and each clue is a finding to weigh: which hypothesis it counts for and whether it weighs more when present or absent. Multimedia brings electrocardiograms, images and auscultation sounds as clues, good for training the description of the finding.

Checklist for interpreting signs and symptoms

1. Did I take a complete history before thinking about tests?
2. Did I write the main hypothesis before the physical examination?
3. Did I ask which hypothesis each finding counts for?
4. Did I separate the findings that weigh when present from those that weigh when absent?
5. Did I record the relevant negatives in the problem summary?
6. Did I look for a review in the Rational Clinical Examination series on the complaint?
7. Did I confirm with someone the sign that decides the hypothesis?
8. Did I describe the finding before naming it?
9. Did I see whether the whole picture fits, and not just the isolated finding?
10. Did I note whether the physical examination changed the hypothesis from the history?

References

1. Hampton JR, Harrison MJ, Mitchell JR, Prichard JS, Seymour C. Relative contributions of history-taking, physical examination, and laboratory investigation to diagnosis and management of medical outpatients. Br Med J. 1975. https://pubmed.ncbi.nlm.nih.gov/1148666/
2. Peterson MC, Holbrook JH, Von Hales D, Smith NL, Staker LV. Contributions of the history, physical examination, and laboratory investigation in making medical diagnoses. West J Med. 1992. https://pubmed.ncbi.nlm.nih.gov/1536065/
3. Sackett DL. The rational clinical examination. A primer on the precision and accuracy of the clinical examination. JAMA. 1992. https://pubmed.ncbi.nlm.nih.gov/1573753/
4. Wang CS, FitzGerald JM, Schulzer M, Mak E, Ayas NT. Does this dyspneic patient in the emergency department have congestive heart failure? JAMA. 2005. https://pubmed.ncbi.nlm.nih.gov/16234501/
5. Attia J, Hatala R, Cook DJ, Wong JG. The rational clinical examination. Does this adult patient have acute meningitis? JAMA. 1999. https://pubmed.ncbi.nlm.nih.gov/10411200/
6. Metlay JP, Kapoor WN, Fine MJ. Does this patient have community-acquired pneumonia? Diagnosing pneumonia by history and physical examination. JAMA. 1997. https://pubmed.ncbi.nlm.nih.gov/9356004/
7. Spiteri MA, Cook DG, Clarke SW. Reliability of eliciting physical signs in examination of the chest. Lancet. 1988. https://pubmed.ncbi.nlm.nih.gov/2895374/
8. Wipf JE, Lipsky BA, Hirschmann JV, et al. Diagnosing pneumonia by physical examination: relevant or relic? Arch Intern Med. 1999. https://pubmed.ncbi.nlm.nih.gov/10335685/