Short summary

This cohort study, based on Danish National Registers, is expected to provide new knowledge of adult patients with chronic non-malignant pain and opioid use in Denmark for the period of 2000-2014. Epidemiological characteristics concerning disease and treatment-related characteristics will be described, including socio-economic and demographic factors. A need for epidemiological studies to describe chronic non-malignant pain and opioid consumption in Denmark remains, as well as a need to examine whether it is possible to determine risk groups.

Rationale

Chronic non-malignant pain (CNP) is a worldwide challenge that needs to be confronted. It has been estimated that CNP affects around 20% of adults over 16 in Europe. In Denmark, the incidence appears to be high, at around 1.8% per year, accounting for 6000-7000 new cases. The ethology of CNP includes various intensive pain disorders and complications to surgery. Common to CNP is that the condition often leads to extensive significant consequences for both the individual and for society as a whole - consequences such as reduced quality of life, decreased function, family and social difficulties, disability, increased mortality and high healthcare costs. These costs are substantial compared to other major chronic diseases.

Moreover, CNP may lead to opioid consumption. In Denmark, there is a high consumption of opioids, the highest among the five Nordic countries. Epidemiological studies to date have been limited to studies including a limited number of opioid products, focusing primarily on cancer pain, or have been studies of smaller scale and with cross-sectional designs. It is therefore important to acquire new and greater knowledge in this area in order to improve and develop existing treatment, prevent long-term use of opioids, premature deaths and reduce healthcare costs and, not least, to further understand the patient's and family's needs. Accordingly, we suggest a retrospective longitudinal population-based study using Danish National Registers: Nationwide data sources comprising all admissions and diagnosis/outpatient diagnoses; prescribed use of medication for two decades and demographic information since 1966. Data are linked by personal identification numbers without revealing the identity of the individuals involved to the researchers. These centralised comprehensive nationwide databases containing key medical, health care and socio-economic information, are ideal for analysing characteristics of CNP patients and patterns of opioid use, and address the following aims:

1. To determine the distribution and determinants of opioid use among CNP patients during 2000 - 2014
2. To identify the patient, treatment and socioeconomic characteristics as determinants for potential risk groups

Description of the cohort

The cohort consisting of all adults aged 16 years or older who redeemed at least one prescription for an opioid product in the period 2000-2014 (incl.) residing in Denmark. Follow-up minimum one year after the last redeemed opioid prescription or to December 2015. Participants are included at first redeemed prescription for an opioid product using the ATC codes starting with N02AA01 - N02AX06 (61 opioid products). Exclusion criterion: cancer-related opioid treatment. Comparisons using logistic regression analysis between three predefined non-overlapping outcome groups:

1. Individuals with opioid use for more than 1 year
2. Individuals with opioid use for more than 6 months and
3. Individuals with opioid use equal to or less than 6 months.

Data and biological material

Data are accessed through Statistics Denmark using drug prescription data from the National prescription Database; data of diagnoses from the Danish National Hospital Discharge; and socio-demographic information (e.g., income, education, family, housing, emigration) from the Socio-Economic Database, as well as information on death from The Danish Death Register.

The study does not collect biological material.

Collaborating researchers and departments

Department of Neuroanesthesiology, Neurocenter, Copenhagen University Hospital, Rigshospitalet

• Postdoc Carrinna Hansen, PhD, MPH, RN

OPEN Odense Patient Data Explorative Network, Odense University Hospital & Department of Medicine, Holbaek Hospital

• Professor Bo Abrahamsen, MD