Evidence map›Paper›PMID 41449624›Full record

ArticlePharmacotherapy2026

C-Reactive Protein and Neutrophil-To-Lymphocyte Ratio: Can They Be Used Interchangeably in Tracking Clozapine-Related Inflammation?

Nicoline Bihelek, Chad A Bousman, William G Honer, Reza Rafizadeh

Abstract read
In one paragraph

Article in Pharmacotherapy, 2026. The graph could read no effect estimate from its abstract, so it casts no vote on the map. Cited by 1 paper.

0numbers the graph read from it
0cells of the map it votes in
1citing papers in PubMed
–field-weighted citation impact
1 · What the graph read from it

What it found

Each row is one number read from the abstract, on the scale the paper reported it, with its interval. Left of the dashed line favours the treatment, right favours the comparator. Under each row is the sentence it came from. New to these charts? A ten-minute tutorial.

The abstract states no effect estimate the extractor could read, or names no intervention and outcome on the map, so this paper lights no cell and moves no belief. It is still indexed, cited and linked below.

2 · The registry

The trial behind it

Trials whose registry record cites this paper, or whose number appears in the abstract. A trial that started after this paper was published is citing it as background, not reporting it.

Neither the registry nor the abstract names a trial number. If this is a trial report, that itself is worth knowing.

3 · Its place in the literature

Who cites it

1 citing paper in PubMed.

  1. Article
4 · The record

Corrections and comments

PubMed lists nothing against this paper. Absence here is not a guarantee, only a check that was made.

5 · Who and what money

Authors and funding

4 authors.

Nicoline BihelekLower Mainland Pharmacy Services, Vancouver, British Columbia, Canada.
Chad A BousmanDepartments of Psychiatry, Medical Genetics, Physiology & Pharmacology, and Community Health Sciences, University of Calgary, Calgary, Alberta, Canada.ORCID 0000-0001-6303-8696
William G HonerDepartment of Psychiatry, University of British Columbia, Vancouver, British Columbia, Canada.
Reza RafizadehLower Mainland Pharmacy Services, Vancouver, British Columbia, Canada.ORCID 0000-0002-4163-8241

Funding

No grant is acknowledged in the PubMed record.

6 · The paper itself

Abstract

backgroundClozapine initiation often triggers inflammatory responses that can alter metabolism via Cytochrome P450 1A2 (CYP1A2) suppression. Although C-reactive protein (CRP) is the recommended marker, it may be unavailable in community settings. Neutrophil-to-lymphocyte ratio (NLR), routinely measured, could serve as a surrogate, though its value in detecting clozapine-related inflammation and metabolic changes remains unclear.

aimsThis study aimed to assess the relationship between CRP and NLR in individuals treated with clozapine, evaluate whether NLR can act as a proxy for elevated CRP (> 5 mg/L), and determine whether NLR, like CRP, explains variability in clozapine metabolism (concentration to dose (C/D) ratios) after adjusting for covariates.

methodsWe performed a retrospective cohort study of clozapine-treated inpatients at the British Columbia Psychosis Program (2012-2021). Patients with clozapine levels and matched complete blood counts (CBCs) (±7 days) were included, with CRP added when available. Multivariate mixed models assessed associations between CRP, NLR, and clozapine C/D ratios, while receiver operating characteristic (ROC) analyses evaluated NLR as a proxy for elevated CRP.

resultsAmong 150 patients, 760 clozapine serum/CBC pairs and 212 CRP measurements met eligibility criteria. NLR was modestly associated with CRP (estimate = 0.027, p < 0.001). ROC analysis indicated that NLR had limited predictive utility, with an area under the curve (AUC) of 0.640 for detecting CRP > 5 mg/L. Subsequent analyses for higher CRP thresholds (> 10 and > 20 mg/L) produced comparable NLR AUC values of 0.621 and 0.669, respectively. Neutrophil count alone demonstrated marginally better performance but remained similarly limited in predictive value. In multivariate models, CRP but not NLR, was independently associated with clozapine C/D ratios.

conclusionOur findings indicate that although NLR and other hematological indices are easily accessible and may provide some indication of inflammation, they cannot substitute for CRP in guiding clozapine titration decisions. Where CRP is unavailable, NLR > 3 may be cautiously informative, though CRP remains the preferred marker for early detection and dose adjustment to optimize tolerability, adherence, and safety during clozapine initiation.

Indexed as

Antipsychotic AgentsClozapineC-Reactive ProteinInflammationLymphocytesNeutrophilsAdultBiomarkersCohort StudiesFemaleHumansLeukocyte CountMaleMiddle AgedRetrospective StudiesAntipsychotic AgentsBiomarkersClozapineC-Reactive ProteinclozapineCRPinflammationNLRTDM

Identifiers

PMID41449624
PMCPMC12862047

What OpenQuestion holds

Textmetadata
LicenceCC BY-NC
Read underepoch 390

Registered trials

None linked

Read under generation 80e0d062 · epoch 390. Bibliography from PubMed, PubMed Central and OpenAlex; grants from NIH RePORTER; trial links from ClinicalTrials.gov; estimates, votes and beliefs from the OpenQuestion graph.