Prevalence and comorbidity of chronic pain in the German general population

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Abstract

The objectives of this study were to evaluate 1) the prevalence of chronic and neuropathic pain features (NeP); 2) their comorbidities with psychiatric disorders and organic diseases; and 3) their impact on daily life and health care utilization. A random sample of 3011 participants (≥15 years), representative of Germany, was interviewed by telephone. Chronic pain duration was set at three months. Neuropathy, frequency, severity, duration, impacts on functioning, and health care utilizations were investigated. Psychiatric disorders were assessed using DSM-IV-TR criteria. ICD-10 was used for organic diseases. Overall, 26.8% (95% confidence interval: 25.2–28.4%) of the sample reported having pain; 1.9% had acute pain (i.e., lasting less than three months), setting the prevalence of chronic pain at 24.9%. More precisely, 18.4% of the sample had non-neuropathic chronic pain (non-NeP) and 6.5% had NeP features. NeP presented several differences from non-NeP: individuals NeP features reported higher pain severity and higher interference of pain in daily activities compared to the non-NeP group. Individuals suffering from a major depressive disorder were three times more likely to have non-NeP and six times more likely to have NeP features. Individuals with obesity, diabetes, hypertension, cerebrovascular diseases, diseases of the nervous system, and diseases of the blood and blood-forming organs were at higher risk of having NeP but not non-NeP. These differences in prevalence and comorbidities between non-NeP and NeP features show how important it is to regard these different modalities of pain separately. Participants with NeP features suffer more and have greater impairment in their daily life than those with non-NeP.

Introduction

Chronic pain is a common condition that affects between 25% and 35% (Breivik et al., 2006) but up to 45% of the general population (Ohayon and Schatzberg, 2010) and is one of the most common reasons for primary care consultations (Mäntyselkä et al., 2001). Neuropathic pain (NeP) is a common pain syndrome affecting up to 25% of individuals with chronic pain.

The International Association for the Study of Pain (IASP) defined NeP as “Pain caused by a lesion or disease of the somatosensory nervous system” (Merskey and Bogduk, 1994, updated in 2011). Characteristic symptoms associated with NeP include a sensation of burning, of electric shocks, and paresthesias.

There is little epidemiological data on NeP syndromes. Most of our knowledge has derived from studies within certain patient groups that present with symptoms of NeP and that have a common disease that predisposes them for NeP. This, however, bears the bias of not recognizing the impact of NeP symptoms in the general population. Few population-based studies exist on NeP symptoms and most of them have utilized different tools to identify NeP. In the past 10 years, five screening tools for NeP have been developed: 1) the Leeds Assessment of Neuropathic Symptoms and Signs (LANSS) (Bennett, 2001, Bennett et al., 2005); 2) the Neuropathic Pain Questionnaire (NPQ) (Krause and Backonja, 2003); 3) the DN4Q (“Douleur Neuropathique en 4 questions” or Neuropathic Pain in 4 questions) (Bouhassira et al., 2005); 4) painDETECT (Freynhagen et al., 2006); and 5) the ID-Pain (Portenoy, 2006). Each of these tools is very similar in language and uses 7 to 12 items to capture the unique characteristics of NeP.

Two of these screening tools, the self-report LANSS (S-LANSS) and the DN4Q, have been used in epidemiological studies to assess the prevalence of NeP. A first study using the S-LANSS was conducted with a random sample of 6000 adults extracted from 6 family practices in 3 UK cities; 3002 questionnaires were completed. A prevalence of 48% of any chronic pain was found; NeP (S-LANSS score ≥12) had a prevalence of 8.2% (Torrance et al., 2006). Another study conducted in Austria (Gustorff et al., 2008) with 7707 individuals between 25 and 75 years of age used a web-administered version of the S-LANSS. Several exclusion criteria based on medical history were applied prior to the administration of the S-LANSS. A NeP prevalence of 3.3% was reported.

Two studies have used the DN4Q to assess NeP. In the first study (Bouhassira et al., 2008), the DN4Q was sent by mail and returned by 23,712 French individuals. A score of ≥3 on the DN4Q was considered indicative of NeP. Overall, 31.7% of the sample reported chronic daily pain for more than 3 months. The prevalence of NeP was 6.9% in the sample. The second study was conducted in the province of Alberta (Canada). The DN4Q was administered by telephone to 1207 randomly selected individuals 18 years or older. Overall, 35% of the sample reported daily, or nearly daily, chronic pain of ≥3 months. The prevalence of NeP was 17.9% (DN4Q score ≥ 3) (Toth et al., 2009).

Thus, a large variability in the prevalence of NeP in the general population exists. This may reflect the differences in the diagnostic tools used. This also demonstrates the lack of a population-based design that provides much more data on each subject than just a brief diagnostic interview on NeP symptoms involving fewer than 30 items per individual.

The objectives of this study, therefore, were to 1) measure the prevalence of chronic pain and NeP in the German general population; 2) embed the data on prevalence in the context of daily life in the general population by estimating the impact of chronic pain and NeP on daily life; 3) describe the use of health care resources in participants with chronic pain and NeP; and, finally, 4) assess comorbid conditions associated with chronic pain and NeP.

Section snippets

Sample

This study was performed in 2007. The target population was individuals 15 years and older living in Germany. Of 3786 eligible participants, 3011 completed interviews were obtained providing a 79.5% cooperation rate, using CASRO (Council of American Survey Research Organizations) standards.

Procedures

In the first stage, telephone numbers were randomly selected in proportion to the population size of each geographic area of Germany. Phone number selection was performed using a computerized residential

Characteristics of the sample

A total of 3011 individuals between 15 and 100 years of age participated in the study. Demographic characteristics of the sample are presented in Table 1, Table 2, including age distribution. Women represented over half of the sample. Nearly half of the sample were employed (48.6%) and 9.6% were in school.

Prevalence of chronic and neuropathic pain

A total of 26.8% [25.2–28.4%] of the sample reported having pain: 1.9% had acute pain and 24.9% had chronic pain (i.e., lasting for at least 3 months).

Chronic pain was divided into

Discussion

This was a study that measured the prevalence of chronic and neuropathic pain in the general population of Germany. There are few studies that have used validated measures on chronic pain with a specific focus on the separation of neuropathic pain features at a community level in Europe. In this assessment of the general German population, the overall prevalence of chronic pain (26.8%) was higher to the prevalence measured in the pan-European study by Breivik in 2006, which reported a

Role of funding source

Funding for this study was provided by Pfizer Inc. The supporting entity had no role in the design and conduct of the study (collection, management, analysis) nor in the interpretation of the data. The supporting entity has not seen the manuscript and had no role in the decision to submit the paper for publication.

The author had full access to all of the data in the study and takes responsibility for the integrity of the data and the accuracy of the data analysis.

Contributors

No contributor.

Conflict of interest

None.

Acknowledgement

This study was supported by an unrestricted grant from Pfizer Inc.

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