Portuguese Version of the Intentional Non-Adherence Scale: Validation in a Population of Chronic Pain Patients

Objective: Despite the effectiveness of pain medicines, nonadherence to prescribed medication remains a major problem faced by healthcare systems. The aim of present study was to perform the translation, cultural adaptation, and validation of the Intentional Non-Adherence Scale (INAS) for the European Portuguese language in a sample of chronic pain patients.

Methods: A Portuguese version of the INAS scale was constructed through a process of translation, back translation, and expert’s panel evaluation. A total of 133 chronic pain patients were selected from two chronic pain clinics from tertiary hospitals in Porto, Portugal. The protocol interview included the assessment of pain beliefs (PBPI), beliefs about medicine (BMQ), medication adherence (MARS-P9), and two direct questions about adherence previously validated.

Results: The internal consistency in all subscales was α = 0.902 for testing treatment; α = 0.930 for mistrust treatment; α = 0.917 for resisting treatment; and α = 0.889 for resisting illness. Exploratory and confirmatory factor analysis revealed a four-factor structure that explained 74% of the variance. The construct validity of the INAS was shown to be adequate, with the majority of the previously defined hypotheses regarding intercorrelations with other measures confirmed.

Conclusion: The Portuguese version of INAS could be a valuable and available instrument for Portuguese researchers and clinicians to assess the intentional nonadherence determinants during the management of chronic pain.

Non-Adherence to Pharmacotherapy: A Prospective Multicentre Study About Its Incidence and Its Causes Perceived by Chronic Pain Patients

OBJECTIVE

Pharmacological interventions remain the cornerstone of chronic pain treatment; however, nearly 40% of the prescription medicines are not taken as prescribed. The present study aims at understanding and describing non-adherence from the perspective of chronic pain patients during a 1-year follow-up study.

METHODS

A cohort of 950 consecutive patients referred to a first consultation in Multidisciplinary Chronic Pain Clinics was followed with a standardized protocol for 1 year. This included assessment of pain characteristics; prescribed medication; therapeutic adherence; effectiveness of treatment, non-adherence and its perceived reasons; clinical outcomes and quality of life. We used a mixed methods approach, including qualitative and quantitative analyses.

RESULTS

Forty-nine percent of the 562 patients who responded to all assessments during follow-up were adherent after 1 year of chronic pain treatment. The core associations between each "non-adherence reason" and Anatomical Therapeutic Chemical Code (ATC) group were perceived side effects (p=0.019) and delayed start (p=0.022) for narcotic analgesics (opioids); perceived non-efficacy (p=0.017) and delayed start (p=0.004) for antiepileptics and anticonvulsants; perceived low necessity (p=0.041) and delayed start (p=0.036) for analgesics antipyretics; change in prescriptions because of a new clinical condition for antidepressants (p=0.024); high concerns (p=0.045) and change in prescriptions because of a new clinical condition (p<0.001) for non-steroidal anti-inflammatory drugs; delayed start (p=0.016) and financial constraints (p=0.018) for other medications.

DISCUSSION

This study emphasizes the patient's perspective regarding non-adherence to pharmacological treatment of chronic pain, providing valuable and novel information to be used in future interventions to help patients make an informed choice about their adherence behavior.

Portuguese version of the Medication Adherence Report Scale (MARS-9): Validation in a population of chronic pain patients

AIM

The aim of present study was to perform the translation, cultural adaptation, and validation of the Medication Adherence Report Scale (MARS-P9) for the European Portuguese language in a sample of chronic pain patients.

METHODS

A Portuguese version of the nine-item MARS (©Professor Rob Horne) scale (MARS-P9) was constructed through a process of translation, back translation, and experts' panel evaluation. A total of 141 chronic pain patients were subsequently evaluated at four time assessments during a 1-year pain medication treatment. The protocol interview included the assessment of pain intensity and interference (BPI), clinical outcomes and quality of life (S-TOPS), and MARS-P9.

RESULTS

The internal consistency coefficient was acceptable for the total scale (α = 0.84). Exploratory factor analysis revealed a two-factor structure (intentional and unintentional nonadherence) that explained 61% of the variance. Convergent and discriminant validity were demonstrated by correlations between MARS scores and pain interference (r = 0.180, P ≤ 0.01) and S-TOPS (r = 0.242, P ≤ 0.05).

CONCLUSION

MARS-P9 has been shown to be an adequate instrument for Portuguese researchers and clinicians to assess the pattern of adherence during the management of chronic pain.