Parsimonious and efficient assessment of health-related quality of life in osteoarthritis research: validation of the Assessment of Quality of Life (AQoL) instrument

Background: The Assessment of Quality of Life (AQoL) utility instrument was psychometrically developed for the general population. This study aimed to explore its potential as an osteoarthritis (OA) outcome measure.

Methods: WOMAC, Lequesne index, SF-36, Visual analogue scales and the AQoL were administered to 222 people with OA. The ability of each questionnaire to detect differences between groups was based on (i) self-rated health (SRH) and, (ii) differences between people on an orthopedic waiting list (WL) vs people with OA in the community (C). Comparisons included effect size, relative efficiency and receiver operator characteristic curves.

Results: All instruments detected differences between groups; however no one instrument exhibited superior efficiency. The AQoL demonstrated strong psychometric properties.

Conclusion: The AQoL has equivalent performance to comparator questionnaires commonly used in OA research and would be a useful adjunct to well-established disease specific scales. The AQoL has important advantages; brevity (12 items), facilitates comparisons between disease groups, and delivers a utility score that can be used in health economic evaluations.

Is change in global self-rated health associated with change in affiliation with a primary care provider? Findings from a longitudinal study from New Zealand

To investigate the association of self-rated health and affiliation with a primary care provider (PCP) in New Zealand.
Methods

We used data from a New Zealand panel study of 22,000 adults. The main exposure was self-rated health, and the main outcome measure was affiliation with a PCP. Fixed effects conditional logistic models were used to control for observed time-varying and unobserved time-invariant confounding.
Results

In any given wave, the odds of being affiliated with a PCP were higher for those in good and fair/poor health relative to those in excellent health. While affiliation for Europeans increased as reported health declined, the odds of being affiliated were lower for Māori respondents reporting very good or good health relative to those in excellent health. No significant differences in the association by age or gender were observed.
Conclusions

Our data support the hypothesis that those in poorer health are more likely to be affiliated with a PCP. Variations in affiliation for Māori could arise for several reasons, including differences in care-seeking behaviour and perceived need of care. It may also mean that the message about the benefits of primary health care is not getting through equally to all population groups.

Is cost-related non-collection of prescriptions associated with a reduction in health? Findings from a large-scale longitudinal study of New Zealand adults

OBJECTIVE: To investigate whether cost-related non-collection of prescription medication is associated with a decline in health. SETTINGS: New Zealand Survey of Family, Income and Employment (SoFIE)-Health. PARTICIPANTS: Data from 17 363 participants with at least two observations in three waves (2004-2005, 2006-2007, 2008-2009) of a panel study were analysed using fixed effects regression modelling. PRIMARY OUTCOME MEASURES: Self-rated health (SRH), physical health (PCS) and mental health scores (MCS) were the health measures used in this study. RESULTS: After adjusting for time-varying confounders, non-collection of prescription items was associated with a 0.11 (95% CI 0.07 to 0.15) unit worsening in SRH, a 1.00 (95% CI 0.61 to 1.40) unit decline in PCS and a 1.69 (95% CI 1.19 to 2.18) unit decline in MCS. The interaction of the main exposure with gender was significant for SRH and MCS. Non-collection of prescription items was associated with a decline in SRH of 0.18 (95% CI 0.11 to 0.25) units for males and 0.08 (95% CI 0.03 to 0.13) units for females, and a decrease in MCS of 2.55 (95% CI 1.67 to 3.42) and 1.29 (95% CI 0.70 to 1.89) units for males and females, respectively. The interaction of the main exposure with age was significant for SRH. For respondents aged 15-24 and 25-64 years, non-collection of prescription items was associated with a decline in SRH of 0.12 (95% CI 0.03 to 0.21) and 0.12 (95% CI 0.07 to 0.17) units, respectively, but for respondents aged 65 years and over, non-collection of prescription items had no significant effect on SRH. CONCLUSION: Our results show that those who do not collect prescription medications because of cost have an increased risk of a subsequent decline in health.