Effects of Smoking on Patients With Chronic Pain

A Propensity-weighted Analysis on the Collaborative Health Outcomes Information Registry

James S. Khan; Jennifer M. Hah; Sean C. Mackey

Disclosures

Pain. 2019;160(10):2374-2379. 

In This Article

Abstract and Introduction

Abstract

Tobacco smoking is associated with adverse health effects, and its relationship to pain is complex. The longitudinal effect of smoking on patients attending a tertiary pain management center is not well established. Using the Collaborative Health Outcomes Information Registry of patients attending the Stanford Pain Management Center from 2013 to 2017, we conducted a propensity-weighted analysis to determine independent effects of smoking on patients with chronic pain. We adjusted for covariates including age, sex, body mass index, depression and anxiety history, ethnicity, alcohol use, marital status, disability, and education. We compared smokers and nonsmokers on pain intensity, physical function, sleep, and psychological and mood variables using self-reported NIH PROMIS outcomes. We also conducted a linear mixed-model analysis to determine effect of smoking over time. A total of 12,368 patients completed the CHOIR questionnaire of which 8584 patients had complete data for propensity analysis. Smokers at time of pain consultation reported significantly worse pain intensities, pain interference, pain behaviors, physical functioning, fatigue, sleep-related impairment, sleep disturbance, anger, emotional support, depression, and anxiety symptoms than nonsmokers (all P < 0.001). In mixed-model analysis, smokers tended to have worse pain interference, fatigue, sleep-related impairment, anger, emotional support, and depression over time compared with nonsmokers. Patients with chronic pain who smoke have worse pain, functional, sleep, and psychological and mood outcomes compared with nonsmokers. Smoking also has prognostic importance for poor recovery and improvement over time. Further research is needed on tailored therapies to assist people with chronic pain who smoke and to determine an optimal strategy to facilitate smoking cessation.

Introduction

Tobacco smoking remains a significant public health concern. While prevalence rates of smoking have declined over the past decade, approximately 16% of the US adult population continues to smoke cigarettes (approximately 10% in California where this study was conducted).[17,22] Although there are a number of known adverse health effects related to tobacco smoking, studies in the past 2 decades have also documented an association with chronic pain.[28] A meta-analysis of cross-sectional data identified that smokers are approximately 30% more likely to suffer from low back pain.[29] Furthermore, smokers with chronic pain suffer from higher pain intensities and use more opioids than nonsmokers.[16]

The relationship between smoking and pain is complex and seems to be at least in part bidirectional. Nicotine seems to have an acute antinociceptive effect in animals and humans, which is believed to be mediated through agonism of the nicotinic acetylcholine receptors (nAChRs), modulation of the descending pain-inhibitory pathway, and activation of the endogenous opioid system and neuroendocrine system.[6,12,24,33,34] Despite a potential analgesic effect, epidemiological studies suggest that chronic tobacco use increases the risk of persistent pain. A study of patients with subacute low back pain found that smoking status predicted persistence of pain 1 year after onset.[26]

Although most, but not all studies, have documented a positive association between smoking and pain, many of these investigations were of low methodological quality and did not include an adjusted analysis. Smoking is highly associated with certain demographic and socioeconomic factors, and these same factors are also highly associated with chronic pain. Since it is not possible to randomize patients to smoke tobacco, statistical adjustments are needed to mitigate the effect of potential confounders.

Here, we present a propensity-weighted analysis of smokers vs nonsmokers referred for an evaluation at a tertiary academic pain management center. We sought to identify whether smokers at time of consult report significantly worse pain-related, physical function, mood, and psychological outcomes. Furthermore, we conducted a longitudinal analysis to understand the effects of smoking on pain-related outcomes while receiving care at a tertiary care center.

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