Original Article
Clinical
Usefulness of Neutrophil/Lymphocyte Ratio as a Predictor of Atrial Fibrillation: A Meta-analysis

https://doi.org/10.1016/j.arcmed.2015.03.011Get rights and content

Background and Aims

Current evidence suggests that a high neutrophil/lymphocyte ratio (NLR) may increase the risk of atrial fibrillation (AF), but this association is still uncertain. The aim of the comprehensive meta-analysis was to evaluate the potential association between NLR and the risk of AF.

Methods

We conducted a systematic literature search using electronic databases (PubMed, Ovid, Embase, Cochrane Database and Web of Science) to identify the studies reporting the association between NLR and risk of AF. We searched the literature published January 2015 or earlier. We used both fixed-effects and random-effects models to calculate the overall effect estimate. An I2 >50% indicates at least moderate statistical heterogeneity. A sensitivity analysis and subgroup analysis were performed to find the origin of heterogeneity.

Results

We retrieved 11 studies involving a total of 2,766 participants. The combined odds ratio (OR) of incident AF for baseline NLR level was 1.25 (95% confidence interval [CI] 1.16–1.35) with significant heterogeneity across studies (I2 = 82.7%, p <0.01) and for the post-NLR level (following CABG, RFCA and cardioversion) was 1.518 (95% CI 1.076–2.142) with significant heterogeneity across studies (I2 = 93.7%, p = 0.017). We also showed an association between AF recurrence following CABG, RFCA and cardioversion and baseline NLR level (OR 1.517, 95% CI 1.108–2.079) with significant heterogeneity across studies (I2 = 86.8%, p <0.01).

Conclusions

Our comprehensive meta-analysis suggests that the high level of NLR, whether baseline or postsurgery/procedure, is associated with the increased risk of AF recurrence/occurrence.

Introduction

Atrial fibrillation (AF) is the most common sustained cardiac arrhythmia and increases the risk of stroke and death. The role of inflammation in the development of AF is well demonstrated. The relationship between various inflammatory biomarkers and AF has been established in the past few years and several anti-inflammatory therapies are related to AF risk reduction. Elevation of inflammatory biomarkers such as high-sensitive C-reactive protein (hs-CRP) has been associated with increased risk of AF recurrence following successful electrical cardioversion 1, 2 and catheter ablation (3). Neutrophil/lymphocyte ratio (NLR) has emerged as a novel systemic inflammatory marker and a prognostic indicator of adverse cardiovascular diseases 4, 5. Neutrophils represent activated non-specific inflammation and lymphopenia is a marker of poor general heath and physiological stress. NLR reflects the balance between the neutrophil and lymphocyte levels and integrates these two important and opposite immune pathways, which has served as a measure of both systemic inflammation and stress response. Recently, some studies 6, 7, 8, 9, 10, 11, 12 have evaluated the potential association between NLR and development of AF. However, others 13, 14, 15, 16 showed that this association does not exist, which yielded conflicting results. In this comprehensive meta-analysis, we aimed to further investigate the potential association between NLR and risk of AF.

Section snippets

Search Strategies

Two reviewers (QS and KC) systematically and independently searched the online databases of PubMed, Ovid, Embase, Cochrane Database and Web of Science to identify relevant studies. We used the following keywords: ‘Neutrophil/lymphocyte ratio’ or ‘NLR’ and ‘atrial fibrillation’. Titles and abstracts as well as the reference lists of all of the identified reports were examined independently in duplicate by two reviewers (QS and KC) to include potentially relevant studies published before January

Literature Search

A flow diagram of the data search and study selection is presented in Figure 1. A total of 106 studies were found using our search criteria after removing the duplicates: Pubmed 16, Ovid 13, Embase 17, Cochrane Database 42 and Web of Science 18. We identified 42 duplicate studies, which were discarded. The remaining 64 studies were screened further, and we excluded 50 studies because they were either unrelated, irrelevant, review articles or editorials. Full-text studies were then retrieved for

Discussion

In this comprehensive meta-analysis involving 2,766 patients from 11 studies, baseline NLR and post-NLR was a remarkably consistent and strong predictor of AF, although there was significant heterogeneity across the different studies.

AF is the most common cardiac arrhythmia and increases the risk of stroke and death. The prevalence of AF increases due to the aging of the population. Multiple pieces of evidence indicate that AF development and perpetuation depend on the electrophysiological and

Acknowledgments

This work was supported by a grant (81270245 to T.L.) from the National Natural Science Foundation of China.

Conflicts of interest: None.

Financial disclosures: None.

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