The latest medical research on General Medicine / Internal Medicine

The research magnet gathers the latest research from around the web, based on your specialty area. Below you will find a sample of some of the most recent articles from reputable medical journals about general medicine / internal medicine gathered by our medical AI research bot.

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Phase 3 Efficacy Analysis of a Typhoid Conjugate Vaccine Trial in Nepal.

N Engl J

Salmonella Typhi is a major cause of fever in children in low- and middle-income countries. A typhoid conjugate vaccine (TCV) that was recently prequalified by the World Health Organization was shown to be efficacious in a human challenge model, but data from efficacy trials in areas where typhoid is endemic are lacking.

In this phase 3, randomized, controlled trial in Lalitpur, Nepal, in which both the participants and observers were unaware of the trial-group assignments, we randomly assigned children who were between 9 months and 16 years of age, in a 1:1 ratio, to receive either a TCV or a capsular group A meningococcal conjugate vaccine (MenA) as a control. The primary outcome was typhoid fever confirmed by blood culture. We present the prespecified analysis of the primary and main secondary outcomes (including an immunogenicity subgroup); the 2-year trial follow-up is ongoing.

A total of 10,005 participants received the TCV and 10,014 received the MenA vaccine. Blood culture-confirmed typhoid fever occurred in 7 participants who received TCV (79 cases per 100,000 person-years) and in 38 who received MenA vaccine (428 cases per 100,000 person-years) (vaccine efficacy, 81.6%; 95% confidence interval, 58.8 to 91.8; P<0.001). A total of 132 serious adverse events (61 in the TCV group and 71 in the MenA vaccine group) occurred in the first 6 months, and 1 event (pyrexia) was identified as being vaccine-related; the participant remained unaware of the trial-group assignment. Similar rates of adverse events were noted in the two trial groups; fever developed in 5.0% of participants in the TCV group and 5.4% in the MenA vaccine group in the first week after vaccination. In the immunogenicity subgroup, seroconversion (a Vi IgG level that at least quadrupled 28 days after vaccination) was 99% in the TCV group (677 of 683 participants) and 2% in the MenA vaccine group (8 of 380 participants).

A single dose of TCV was immunogenic and effective in reducing S. Typhi bacteremia in children 9 months to 16 years of age. (Funded by the Bill and Melinda Gates Foundation; Current Controlled Trials number, ISRCTN43385161.).

Endoscopic or Surgical Myotomy in Patients with Idiopathic Achalasia.

N Engl J

Pneumatic dilation and laparoscopic Heller's myotomy (LHM) are established treatments for idiopathic achalasia. Peroral endoscopic myotomy (POEM) is a less invasive therapy with promising early study results.

In a multicenter, randomized trial, we compared POEM with LHM plus Dor's fundoplication in patients with symptomatic achalasia. The primary end point was clinical success, defined as an Eckardt symptom score of 3 or less (range, 0 to 12, with higher scores indicating more severe symptoms of achalasia) without the use of additional treatments, at the 2-year follow-up; a noninferiority margin of -12.5 percentage points was used in the primary analysis. Secondary end points included adverse events, esophageal function, Gastrointestinal Quality of Life Index score (range, 0 to 144, with higher scores indicating better function), and gastroesophageal reflux.

A total of 221 patients were randomly assigned to undergo either POEM (112 patients) or LHM plus Dor's fundoplication (109 patients). Clinical success at the 2-year follow-up was observed in 83.0% of patients in the POEM group and 81.7% of patients in the LHM group (difference, 1.4 percentage points; 95% confidence interval [CI], -8.7 to 11.4; P = 0.007 for noninferiority). Serious adverse events occurred in 2.7% of patients in the POEM group and 7.3% of patients in the LHM group. Improvement in esophageal function from baseline to 24 months, as assessed by measurement of the integrated relaxation pressure of the lower esophageal sphincter, did not differ significantly between the treatment groups (difference, -0.75 mm Hg; 95% CI, -2.26 to 0.76), nor did improvement in the score on the Gastrointestinal Quality of Life Index (difference, 0.14 points; 95% CI, -4.01 to 4.28). At 3 months, 57% of patients in the POEM group and 20% of patients in the LHM group had reflux esophagitis, as assessed by endoscopy; at 24 months, the corresponding percentages were 44% and 29%.

In this randomized trial, POEM was noninferior to LHM plus Dor's fundoplication in controlling symptoms of achalasia at 2 years. Gastroesophageal reflux was more common among patients who underwent POEM than among those who underwent LHM. (Funded by the European Clinical Research Infrastructure Network and others; number, NCT01601678.).

Ubrogepant for the Treatment of Migraine.

N Engl J

Ubrogepant is an oral, small-molecule calcitonin gene-related peptide receptor antagonist for acute migraine treatment.

We conducted a randomized trial to evaluate the efficacy, safety, and side-effect profile of ubrogepant. We assigned adults with migraine, with or without aura, in a 1:1:1 ratio to receive an initial dose of placebo, ubrogepant at a dose of 50 mg, or ubrogepant at a dose of 100 mg for treatment of a single migraine attack, with the option to take a second dose. The coprimary efficacy end points were freedom from pain at 2 hours after the initial dose and absence of the most bothersome migraine-associated symptom at 2 hours. Secondary end points included pain relief (at 2 hours), sustained pain relief (from 2 to 24 hours), sustained freedom from pain (from 2 to 24 hours), and absence of symptoms associated with migraine (photophobia, phonophobia, and nausea) at 2 hours.

A total of 1672 participants were enrolled; 559 were assigned to receive placebo, 556 to receive 50 mg of ubrogepant, and 557 to receive 100 mg of ubrogepant. The percentage of participants who had freedom from pain at 2 hours was 11.8% in the placebo group, 19.2% in the 50-mg ubrogepant group (P = 0.002, adjusted for multiplicity, for the comparison with placebo), and 21.2% in the 100-mg ubrogepant group (P<0.001). The percentage of participants who had freedom from the most bothersome symptom at 2 hours was 27.8% in the placebo group, 38.6% in the 50-mg ubrogepant group (P = 0.002), and 37.7% in the 100-mg ubrogepant group (P = 0.002). Adverse events within 48 hours after the initial or optional second dose were reported in 12.8% of participants in the placebo group, in 9.4% in the 50-mg ubrogepant group, and in 16.3% in the 100-mg ubrogepant group. The most common adverse events were nausea, somnolence, and dry mouth (reported in 0.4 to 4.1%); these events were more frequent in the 100-mg ubrogepant group (reported in 2.1 to 4.1%). Serious adverse events reported within 30 days in the ubrogepant groups included appendicitis, spontaneous abortion, pericardial effusion, and seizure; none of the events occurred within 48 hours after the dose.

A higher percentage of participants who received ubrogepant than of those who received placebo had freedom from pain and absence of the most bothersome symptom at 2 hours after the dose. The most commonly reported adverse events were nausea, somnolence, and dry mouth. Further trials are needed to determine the durability and safety of ubrogepant for acute migraine treatment and to compare it with other drugs for migraine. (Funded by Allergan; number, NCT02828020.).

Effectiveness of a Brief Self-determination Theory-Based Smoking Cessation Intervention for Smokers at Emergency Departments in Hong Kong: A Randomized Clinical Trial.

JAMA Internal Medicine

Clinicians have an opportunity to provide smoking cessation interventions to smokers who present to emergency departments (EDs). The effectiveness of a brief intervention based on self-determination theory for smoking cessation is uncertain.

To examine the effectiveness of a brief intervention based on self-determination theory for smoking cessation (immediate or progressive) among Chinese smokers presenting at EDs in Hong Kong.

This single-blind, multicenter intent-to-treat randomized clinical trial was conducted at the EDs of 4 major acute care hospitals in different districts of Hong Kong. In total, 1571 smokers 18 years or older who presented at 4 major EDs between July 4, 2015, and March 17, 2017, were randomized into an intervention group (n = 787) and a control group (n = 784).

The intervention group received brief advice (about 1 minute) and could choose their own quit schedules (immediate or progressive). The control group received a smoking cessation leaflet.

Follow-up visits were conducted at 1, 3, 6, and 12 months. The primary outcome measure, by intent to treat, was biochemically validated abstinence at 6 months.

Participants (N = 1571) included 1381 men (87.9%); the mean (SD) age at baseline was 47.4 (16.4) years. Among participants who self-reported abstinence at 6 months, 50.3% (85 of 169) had biochemical validation by both an exhaled carbon monoxide test and a saliva cotinine test. Compared with the control group, the intervention group had statistically higher biochemically validated abstinence at 6 months: 6.7% (53 of 787) vs 2.8% (22 of 784) (P < .001), with an adjusted relative risk of 3.21 (95% CI, 1.74-5.93; P < .001). The intervention group also had higher self-reported quit rates at 6 months (12.2% [96 of 787] vs 9.3% [73 of 784], P = .04) and 12 months (13.0% [102 of 787] vs 8.5% [67 of 784], P < .01), as well as higher biochemically validated abstinence at 12 months (7.0% [55 of 787] vs 3.7% [29 of 784], P < .001). The additional cost for each intervention group participant was US $0.47, with an estimated gain of 0.0238 quality-adjusted life-year. The incremental cost per quality-adjusted life-year (US $19.53) fell within acceptable thresholds.

This brief, low-cost self-determination theory-based intervention for smokers presenting at EDs effectively increased the biochemically validated quit rate at 6 months. If delivered routinely, such a simple intervention may offer a cost-effective and sustainable approach to help many smokers quit smoking. identifier: NCT02660957.

Updated guidelines for the management of paracetamol poisoning in Australia and New Zealand.

Medical Journal of Australia

Paracetamol is a common agent taken in deliberate self-poisoning and in accidental overdose in adults and children. Paracetamol poisoning is the commonest cause of severe acute liver injury. Since the publication of the previous guidelines in 2015, several studies have changed practice. A working group of experts in the area, with representation from all Poisons Information Centres of Australia and New Zealand, were brought together to produce an updated evidence-based guidance.

The optimal management of most patients with paracetamol overdose is usually straightforward. Patients who present early should be given activated charcoal. Patients at risk of hepatotoxicity should receive intravenous acetylcysteine. The paracetamol nomogram is used to assess the need for treatment in acute immediate release paracetamol ingestions with a known time of ingestion. Cases that require different management include modified release paracetamol overdoses, large or massive overdoses, accidental liquid ingestion in children, and repeated supratherapeutic ingestions.

The new guidelines recommend a two-bag acetylcysteine infusion regimen (200 mg/kg over 4 h, then 100 mg/kg over 16 h). This has similar efficacy but significantly reduced adverse reactions compared with the previous three-bag regimen. Massive paracetamol overdoses that result in high paracetamol concentrations more than double the nomogram line should be managed with an increased dose of acetylcysteine. All potentially toxic modified release paracetamol ingestions (≥ 10 g or ≥ 200 mg/kg, whichever is less) should receive a full course of acetylcysteine. Patients ingesting ≥ 30 g or ≥ 500 mg/kg should receive increased doses of acetylcysteine.

Association of the Work Schedules of Hospitalists With Patient Outcomes of Hospitalization.

JAMA Internal Medicine

The working schedules of hospitalists vary widely. Discontinuous schedules, such as 24 hours on and 48 hours off, result in several hospitalists providing care during a patient's hospital stay. Poor continuity of care during hospitalization may be associated with poor patient outcomes.

To determine whether admitted patients receiving care from hospitalists with more discontinuous schedules experience worse outcomes.

This retrospective cohort study used conditional models to assess Medicare claims data for 114 777 medical admissions of patients with a 3-day to 6-day length of stay from January 1, 2014, through November 30, 2016, who received all general medical care from hospitalists in 229 hospitals in Texas. Data were analyzed from November 2018 to June 2019.

For each admission, the weighted mean of schedule continuity for the treating hospitalists, assessed as the percentage of all their working days in that year that were part of a block of 7 or more consecutive working days, was calculated.

The primary outcome was patient mortality in the 30 days after discharge. Secondary outcomes were readmission rates and Medicare costs in the 30 days after discharge, and discharge destination.

Of the 114 777 patient admissions, the mean (SD) age was 79.9 (8.3) years, and 70 047 (61.0%) were women. For admissions in the lowest quartile for continuity of hospitalist schedules, the hospitalists providing care worked 0% to 30% of their total working days as part of a block of 7 or more consecutive days vs 67% to 100% for hospitalists providing care for patients in the highest quartile for continuity. Patient characteristics were not associated with the continuity of working schedules for the hospitalist(s) providing care. In conditional logistic regression models, admitted patients cared for by hospitalists in the highest quartile of schedule continuity (vs the lowest quartile) had lower 30-day mortality after discharge (adjusted odds ratio [aOR], 0.88; 95% CI, 0.81-0.95), lower readmission rates (aOR, 0.94; 95% CI, 0.90-0.99), higher rates of discharge to the home (aOR, 1.08; 95% CI, 1.03-1.13), and lower 30-day postdischarge costs (-$223; 95% CI, -$441 to -$7). The results were similar across a range of different methods for defining continuity of hospitalist schedules and selecting the cohort.

Hospitalist schedules vary widely. Admitted patients receiving care from hospitalists with schedules that promote inpatient continuity of care may experience better outcomes of hospitalization.

Association of Anticoagulant Therapy With Risk of Fracture Among Patients With Atrial Fibrillation.

JAMA Internal Medicine

Warfarin is prescribed to patients with atrial fibrillation (AF) for the prevention of cardioembolic complications. Whether warfarin adversely affects bone health is controversial. The availability of alternate direct oral anticoagulant (DOAC) options now make it possible to evaluate the comparative safety of warfarin in association with fracture risk.

To test the hypothesis that, among patients with nonvalvular AF, use of DOACs vs warfarin is associated with lower risk of incident fracture.

This comparative effectiveness cohort study used the MarketScan administrative claims databases to identify patients with nonvalvular AF and who were prescribed oral anticoagulants from January 1, 2010, through September 30, 2015. To reduce confounding, patients were matched on age, sex, CHA2DS2-VASc (congestive heart failure, hypertension, age [>65 years = 1 point; >75 years = 2 points], diabetes, and previous stroke/transient ischemic attack [2 points], vascular disease) score, and high-dimensional propensity scores. The final analysis included 167 275 patients with AF. Data were analyzed from February 27, 2019 to September 18, 2019.

Warfarin and DOACs (dabigatran etexilate, rivaroxaban, and apixaban).

Incident hip fracture, fracture requiring hospitalization, and all clinical fractures (identified using inpatient or outpatient claims) defined by International Classification of Diseases, Ninth Revision, Clinical Modification codes.

In the study population of 167 275 patients with AF (38.0% women and 62.0% men; mean [SD] age, 68.9 [12.5] years), a total of 817 hip fractures, 2013 hospitalized fractures, and 7294 total fractures occurred during a mean (SD) follow-up of 16.9 (13.7) months. In multivariable-adjusted, propensity score-matched Cox proportional hazards regression models, relative to new users of warfarin, new users of DOACs tended to be at lower risk of fractures requiring hospitalization (hazard ratio [HR], 0.87; 95% CI, 0.79-0.96) and all clinical fractures (HR, 0.93; 95% CI, 0.88-0.98), whereas the association with hip fractures (HR, 0.91; 95% CI, 0.78-1.07) was not statistically significant. When comparing individual DOACs with warfarin, the strongest findings were for apixaban (HR for hip fracture, 0.67 [95% CI, 0.45-0.98]; HR for fractures requiring hospitalization, 0.60 [95% CI, 0.47-0.78]; and HR for all clinical fractures, 0.86 [95% CI, 0.75-0.98]). In subgroup analyses, DOACs appeared more beneficial among patients with AF who also had a diagnosis of osteoporosis than among those without a diagnosis of osteoporosis.

In this real-world population of 167 275 patients with AF, use of DOACs-particularly apixaban-compared with warfarin use was associated with lower fracture risk. These associations were more pronounced among patients with a diagnosis of osteoporosis. Given the potential adverse effects of warfarin on bone health, these findings suggest that caution should be used when prescribing warfarin to patients with AF at high risk of fracture.

A Randomized, Controlled Trial of Ebola Virus Disease Therapeutics.

N Engl J

Although several experimental therapeutics for Ebola virus disease (EVD) have been developed, the safety and efficacy of the most promising therapies need to be assessed in the context of a randomized, controlled trial.

We conducted a trial of four investigational therapies for EVD in the Democratic Republic of Congo, where an outbreak began in August 2018. Patients of any age who had a positive result for Ebola virus RNA on reverse-transcriptase-polymerase-chain-reaction assay were enrolled. All patients received standard care and were randomly assigned in a 1:1:1:1 ratio to intravenous administration of the triple monoclonal antibody ZMapp (the control group), the antiviral agent remdesivir, the single monoclonal antibody MAb114, or the triple monoclonal antibody REGN-EB3. The REGN-EB3 group was added in a later version of the protocol, so data from these patients were compared with those of patients in the ZMapp group who were enrolled at or after the time the REGN-EB3 group was added (the ZMapp subgroup). The primary end point was death at 28 days.

A total of 681 patients were enrolled from November 20, 2018, to August 9, 2019, at which time the data and safety monitoring board recommended that patients be assigned only to the MAb114 and REGN-EB3 groups for the remainder of the trial; the recommendation was based on the results of an interim analysis that showed superiority of these groups to ZMapp and remdesivir with respect to mortality. At 28 days, death had occurred in 61 of 174 patients (35.1%) in the MAb114 group, as compared with 84 of 169 (49.7%) in the ZMapp group (P = 0.007), and in 52 of 155 (33.5%) in the REGN-EB3 group, as compared with 79 of 154 (51.3%) in the ZMapp subgroup (P = 0.002). A shorter duration of symptoms before admission and lower baseline values for viral load and for serum creatinine and aminotransferase levels each correlated with improved survival. Four serious adverse events were judged to be potentially related to the trial drugs.

Both MAb114 and REGN-EB3 were superior to ZMapp in reducing mortality from EVD. Scientifically and ethically sound clinical research can be conducted during disease outbreaks and can help inform the outbreak response. (Funded by the National Institute of Allergy and Infectious Diseases and others; PALM number, NCT03719586.).

Supplemental MRI Screening for Women with Extremely Dense Breast Tissue.

N Engl J

Extremely dense breast tissue is a risk factor for breast cancer and limits the detection of cancer with mammography. Data are needed on the use of supplemental magnetic resonance imaging (MRI) to improve early detection and reduce interval breast cancers in such patients.

In this multicenter, randomized, controlled trial in the Netherlands, we assigned 40,373 women between the ages of 50 and 75 years with extremely dense breast tissue and normal results on screening mammography to a group that was invited to undergo supplemental MRI or to a group that received mammography screening only. The groups were assigned in a 1:4 ratio, with 8061 in the MRI-invitation group and 32,312 in the mammography-only group. The primary outcome was the between-group difference in the incidence of interval cancers during a 2-year screening period.

The interval-cancer rate was 2.5 per 1000 screenings in the MRI-invitation group and 5.0 per 1000 screenings in the mammography-only group, for a difference of 2.5 per 1000 screenings (95% confidence interval [CI], 1.0 to 3.7; P<0.001). Of the women who were invited to undergo MRI, 59% accepted the invitation. Of the 20 interval cancers that were diagnosed in the MRI-invitation group, 4 were diagnosed in the women who actually underwent MRI (0.8 per 1000 screenings) and 16 in those who did not accept the invitation (4.9 per 1000 screenings). The MRI cancer-detection rate among the women who actually underwent MRI screening was 16.5 per 1000 screenings (95% CI, 13.3 to 20.5). The positive predictive value was 17.4% (95% CI, 14.2 to 21.2) for recall for additional testing and 26.3% (95% CI, 21.7 to 31.6) for biopsy. The false positive rate was 79.8 per 1000 screenings. Among the women who underwent MRI, 0.1% had either an adverse event or a serious adverse event during or immediately after the screening.

The use of supplemental MRI screening in women with extremely dense breast tissue and normal results on mammography resulted in the diagnosis of significantly fewer interval cancers than mammography alone during a 2-year screening period. (Funded by the University Medical Center Utrecht and others; DENSE number, NCT01315015.).

Randomized Trial of Three Anticonvulsant Medications for Status Epilepticus.

N Engl J

The choice of drugs for patients with status epilepticus that is refractory to treatment with benzodiazepines has not been thoroughly studied.

In a randomized, blinded, adaptive trial, we compared the efficacy and safety of three intravenous anticonvulsive agents - levetiracetam, fosphenytoin, and valproate - in children and adults with convulsive status epilepticus that was unresponsive to treatment with benzodiazepines. The primary outcome was absence of clinically evident seizures and improvement in the level of consciousness by 60 minutes after the start of drug infusion, without additional anticonvulsant medication. The posterior probabilities that each drug was the most or least effective were calculated. Safety outcomes included life-threatening hypotension or cardiac arrhythmia, endotracheal intubation, seizure recurrence, and death.

A total of 384 patients were enrolled and randomly assigned to receive levetiracetam (145 patients), fosphenytoin (118), or valproate (121). Reenrollment of patients with a second episode of status epilepticus accounted for 16 additional instances of randomization. In accordance with a prespecified stopping rule for futility of finding one drug to be superior or inferior, a planned interim analysis led to the trial being stopped. Of the enrolled patients, 10% were determined to have had psychogenic seizures. The primary outcome of cessation of status epilepticus and improvement in the level of consciousness at 60 minutes occurred in 68 patients assigned to levetiracetam (47%; 95% credible interval, 39 to 55), 53 patients assigned to fosphenytoin (45%; 95% credible interval, 36 to 54), and 56 patients assigned to valproate (46%; 95% credible interval, 38 to 55). The posterior probability that each drug was the most effective was 0.41, 0.24, and 0.35, respectively. Numerically more episodes of hypotension and intubation occurred in the fosphenytoin group and more deaths occurred in the levetiracetam group than in the other groups, but these differences were not significant.

In the context of benzodiazepine-refractory convulsive status epilepticus, the anticonvulsant drugs levetiracetam, fosphenytoin, and valproate each led to seizure cessation and improved alertness by 60 minutes in approximately half the patients, and the three drugs were associated with similar incidences of adverse events. (Funded by the National Institute of Neurological Disorders and Stroke; ESETT number, NCT01960075.).

Trial of Satralizumab in Neuromyelitis Optica Spectrum Disorder.

N Engl J

Neuromyelitis optica spectrum disorder (NMOSD) is an autoimmune disease of the central nervous system and is associated with autoantibodies to anti-aquaporin-4 (AQP4-IgG) in approximately two thirds of patients. Interleukin-6 is involved in the pathogenesis of the disorder. Satralizumab is a humanized monoclonal antibody targeting the interleukin-6 receptor. The efficacy of satralizumab added to immunosuppressant treatment in patients with NMOSD is unclear.

In a phase 3, randomized, double-blind, placebo-controlled trial, we randomly assigned, in a 1:1 ratio, patients with NMOSD who were seropositive or seronegative for AQP4-IgG to receive either satralizumab, at a dose of 120 mg, or placebo, administered subcutaneously at weeks 0, 2, and 4 and every 4 weeks thereafter, added to stable immunosuppressant treatment. The primary end point was the first protocol-defined relapse in a time-to-event analysis. Key secondary end points were the change from baseline to week 24 in the visual-analogue scale (VAS) pain score (range, 0 to 100, with higher scores indicating more pain) and the Functional Assessment of Chronic Illness Therapy-Fatigue (FACIT-F) score (range, 0 to 52, with lower scores indicating more fatigue). Safety was also assessed.

A total of 83 patients were enrolled, with 41 assigned to the satralizumab group and 42 to the placebo group. The median treatment duration with satralizumab in the double-blind period was 107.4 weeks. Relapse occurred in 8 patients (20%) receiving satralizumab and in 18 (43%) receiving placebo (hazard ratio, 0.38; 95% confidence interval [CI], 0.16 to 0.88). Multiple imputation for censored data resulted in hazard ratios ranging from 0.34 to 0.44 (with corresponding P values of 0.01 to 0.04). Among 55 AQP4-IgG-seropositive patients, relapse occurred in 11% of those in the satralizumab group and in 43% of those in the placebo group (hazard ratio, 0.21; 95% CI, 0.06 to 0.75); among 28 AQP4-IgG-seronegative patients, relapse occurred in 36% and 43%, respectively (hazard ratio, 0.66; 95% CI, 0.20 to 2.24). The between-group difference in the change in the mean VAS pain score was 4.08 (95% CI, -8.44 to 16.61); the between-group difference in the change in the mean FACIT-F score was -3.10 (95% CI, -8.38 to 2.18). The rates of serious adverse events and infections did not differ between groups.

Among patients with NMOSD, satralizumab added to immunosuppressant treatment led to a lower risk of relapse than placebo but did not differ from placebo in its effect on pain or fatigue. (Funded by Chugai Pharmaceutical; number, NCT02028884.).

Diagnosis of Pulmonary Embolism with d-Dimer Adjusted to Clinical Probability.

N Engl J

Retrospective analyses suggest that pulmonary embolism is ruled out by a d-dimer level of less than 1000 ng per milliliter in patients with a low clinical pretest probability (C-PTP) and by a d-dimer level of less than 500 ng per milliliter in patients with a moderate C-PTP.

We performed a prospective study in which pulmonary embolism was considered to be ruled out without further testing in outpatients with a low C-PTP and a d-dimer level of less than 1000 ng per milliliter or with a moderate C-PTP and a d-dimer level of less than 500 ng per milliliter. All other patients underwent chest imaging (usually computed tomographic pulmonary angiography). If pulmonary embolism was not diagnosed, patients did not receive anticoagulant therapy. All patients were followed for 3 months to detect venous thromboembolism.

A total of 2017 patients were enrolled and evaluated, of whom 7.4% had pulmonary embolism on initial diagnostic testing. Of the 1325 patients who had a low C-PTP (1285 patients) or moderate C-PTP (40 patients) and a negative d-dimer test (i.e., <1000 or <500 ng per milliliter, respectively), none had venous thromboembolism during follow-up (95% confidence interval [CI], 0.00 to 0.29%). These included 315 patients who had a low C-PTP and a d-dimer level of 500 to 999 ng per milliliter (95% CI, 0.00 to 1.20%). Of all 1863 patients who did not receive a diagnosis of pulmonary embolism initially and did not receive anticoagulant therapy, 1 patient (0.05%; 95% CI, 0.01 to 0.30) had venous thromboembolism. Our diagnostic strategy resulted in the use of chest imaging in 34.3% of patients, whereas a strategy in which pulmonary embolism is considered to be ruled out with a low C-PTP and a d-dimer level of less than 500 ng per milliliter would result in the use of chest imaging in 51.9% (difference, -17.6 percentage points; 95% CI, -19.2 to -15.9).

A combination of a low C-PTP and a d-dimer level of less than 1000 ng per milliliter identified a group of patients at low risk for pulmonary embolism during follow-up. (Funded by the Canadian Institutes of Health Research and others; PEGeD number, NCT02483442.).