Home > Methadone-maintained patients in primary care

Grehan, Martin (2016) Methadone-maintained patients in primary care. Drugnet Ireland, Issue 56, Winter 2016, pp. 18-19.

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The use of primary health services by methadone-maintained patients (MMPs) is an under-researched area internationally. The aim of the study described here, conducted by researchers in Trinity College Dublin (TCD), was to examine this issue in the Irish context using a matched case-control study.1 The researchers particularly looked at chronic disease and multi-morbidity among MMPs.


TCD maintains a research network of GP practices throughout the greater Dublin area. Thirteen practices in this network have electronic patient records and provide methadone maintenance treatment (MMT). All 13 agreed to participate.


An MMP had to have attended the practice for both MMT and primary health care for at least one year to be included in the study. In total, 207 MMPs met the criteria, and were matched with 207 controls according to sex, age, practice (to account for geographical variability), and eligibility for the General Medical Services scheme (GMS). The authors considered the combined sample size of 414 one of the major strengths of the study.


Information collected about participants from electronic records included demographic details, chronic disease data, repeat medications, and information relating to smoking, alcohol use, and non-opiate drug use. A number of variables related to health service utilisation were also recorded, such as number of GP and nurse consultations, referrals to hospital, and use of the out-of-hours GP service. Data were extracted from the electronic system using an in-depth form, which included reading all consultation notes. The authors reported some issues with data collection that may have resulted in the under-estimation of some of the variables, especially MMP outpatient attendances. In addition, specialist medicines were excluded from the analysis owing to a lack of systematic documentation in the 13 practices.


Statistical tests conducted included independent samples t-tests, Pearson chi-squared tests, risk estimation, odds ratios (OR), 95% confidence intervals (CI) and binary logistic regression.


There were no statistically significant differences in demographics between the MMP group and the control group: 43% of the sample was female, 57% male; 16% were private patients, 84% GMS patients.


Chronic disease and multi-morbidity

By comparing means using t-tests and by using OR, the authors presented evidence for the increased likelihood of chronic illness among MMPs versus controls. Compared to controls, MMPs were statistically significantly more likely to have: 

  • chronic disease (OR 9.1 [CI 5.4 – 15.1])
  • multi-morbidity, i.e. two or more chronic diseases (OR 6.6 [CI 4.3 – 10.2])
  • repeat medications (OR 5.8 [CI 3.7 – 8.9])
  • history of smoking (OR 4.8 [CI 3.2 – 7.2])
  • excess use of alcohol (OR 2.9 [CI 1.6 – 5.2])
  • non-opiate problem drug use (OR 141.2 [CI 63.3 – 315.3])
  • psychiatric disease (OR 6.1 [CI 3.9 – 9.3])
  • respiratory disease (OR 3.3 [CI 1.9 – 5.9])
  • infectious disease (OR 118.5 [CI 28.8 – 489.9]) 

It is of note that while MMPs were significantly more likely to have a chronic disease (OR 9.1 [CI 5.4 – 15.1], (95% CI), compared to controls, if HIV, and hepatitis B and/or C were excluded, then the OR was less emphatic, dropping to 4.2 (2.7–6.4). As expected, the OR for problem use of non-opiate drugs was highly significant, 141.2 (CI 63.3–315.3).


MMPs have a lower average incidence of cardiovascular disease (0.06 vs 0.14, p=0.04), although the OR for this same category is not significant. This seems to indicate that MMPs may have lower levels of cardiovascular disease than controls, which seems counter-intuitive given the reported differences in the incidence of chronic diseases, and the history of smoking and respiratory disease. While the authors did not explicitly comment, they did observe that often medical problems among MMPs emerge as ‘unanticipated “door-handle symptoms” during time-pressured, protocol-driven methadone appointments’ .


The authors constructed several binary logistic regression models. Of most interest was the model for chronic disease occurrences, age, sex, GMS status, current dose of methadone, and smoking. The model was restricted to MMPs only and the strongest predictor of chronic disease was being a GMS patient with an OR of 7.2 (CI 2.4–22.0). The authors concluded that the data suggested that GMS patients were sicker than non-GMS patients. A link to deprivation was also suggested, though the authors noted that non-GMS MMPs may have been part of a sub-group of MMPs who had shown increases in health and income owing to MMT.


Health Service utilisation

MMPs used their primary care facility on average 32 times a year and, of these, 30 were for MMT. Controls on the other hand had an average of only 3 visits a year. Visits were broken into three non-mutually exclusive categories to allow comparison – ‘medical’, ‘nursing’ and ‘methadone’. MMPs were more likely to have attended for medical or nursing assessments. The majority (87%) of medical assessments and 20% of nursing assessments took place during an MMT consultation.


The study concluded that MMPs cost the health service as a whole more than the baseline cost of MMT:


MMPs had higher levels of health service utilisation at a practice and secondary care level. They generated a higher workload for GPs and increased administrative tasks for primary care services. They spent more time in emergency departments, inpatient beds, and outpatient clinics.



The authors concluded that health care policy must reflect the fact that MMPs are attending GP practices more often than non-MMPs, the strain this places on those services, and the risks associated with a singular focus on drug-related issues. The main recommendations of the authors included a more holistic approach to integrating MMT with general medical needs, and the promotion of better record-keeping with regard to chronic diseases. The authors identified an opportunity to increase the role of the GP practice nurse as the study suggested this resource was under-used in MMT. They also suggested that GPs should be offered incentives to be trained in MMT and any formal review of MMT GP remuneration should take into account the additional workload of taking care of MMT patients.



1 O’Toole J, Hambly R, Cox AM, O'Shea B and Darker C (2014) Methadone-maintained patients in primary care have higher rates of chronic disease and multimorbidity, and use health services more intensively than matched controls. The European Journal of General Practice (20): 275–20. https://www.drugsandalcohol.ie/24352/

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