The use of paracetamol (acetaminophen) among a community sample of people with chronic non-cancer pain prescribed opioids

Background
The regular use of simple analgesics in addition to opioids such as paracetamol (or acetaminophen) is recommended for persistent pain to enhance analgesia. Few studies have examined the frequency and doses of paracetamol among people with chronic non-cancer pain including use above the recommended maximum daily dose.

Aims
To assess (i) the prevalence of paracetamol use among people with chronic non-cancer pain prescribed opioids, (ii) assess the prevalence of paracetamol use above the recommended maximum daily dose and (iii) assess correlates of people who used paracetamol above the recommended maximum daily dose including: age, gender, income, education, pain severity and interference, use of paracetamol/opioid combination analgesics, total opioid dose, depression, anxiety, pain self-efficacy or comorbid substance use, among people prescribed opioids for chronic non-cancer pain.

Methods
This study draws on baseline data collected for the Pain and Opioids IN Treatment (POINT) study and utilises data from 962 interviews and medication diaries. The POINT study is national prospective cohort of people with chronic non-cancer pain prescribed opioids. Participants were recruited from randomly selected pharmacies across Australia.

Results
Sixty-three per cent of the participants had used paracetamol in the past week (95% CI = 59.7–65.8). Among the paracetamol users 22% (95% CI = 19.3–24.6) had used paracetamol/opioid combination analgesics and 4.8% (95% CI = 3.6–6.3) had used paracetamol above the recommended maximum daily dose (i.e. > 4000 mg/day). Following binomial logistic regression (χ2 = 25.98, df = 10, p = 0.004), people who had taken above the recommended maximum daily dose were less likely to have low income (AOR = 0.52, 95% CI = 0.27–0.99), more likely to use paracetamol/opioid combination analgesics (AOR = 2.01, 95% CI = 1.02–3.98) and more likely to take a higher opioid dose (AOR = 1.00, 95% CI = 1.00–1.01).

Conclusion
The majority of people with chronic non-cancer pain prescribed opioids report using paracetamol appropriately. High income, use of paracetamol/opioid combination analgesics and higher opioid dose were independently associated with paracetamol use above the recommended maximum daily dose.