Background A number of studies have computed the minimally important difference (MID) for health-related quality of life instruments. Objective To determine whether there is consistency in the magnitude of MID estimates from different instruments. Methods We conducted a systematic review of the literature to identify studies that computed an MID and contained sufficient information to compute an effect size (ES). Thirty-eight studies fulfilled the criteria, resulting in 62 ESs. Results For all but 6 studies, the MID estimates were close to one half a SD (mean = 0.495, SD = 0.155). There was no consistent relationship with factors such as disease-specific or generic instrument or the number of response options. Negative changes were not associated with larger ESs. Population-based estimation procedures and brief follow-up were associated with smaller ESs, and acute conditions with larger ESs. An explanation for this consistency is that research in psychology has shown that the limit of people's ability to discriminate over a wide range of tasks is approximately 1 part in 7, which is very close to half a SD. Conclusion In most circumstances, the threshold of discrimination for changes in health-related quality of life for chronic diseases appears to be approximately half a SD.

Interpretation of changes in health-related quality of life the remarkable universality of half a standard deviation

Validation of two global impression questionnaires for incontinence.

A lack of clarity exists about the definition and adequate approach for evaluating responsiveness. An overview is presented of different categories of definitions and methods used for calculating responsiveness identified through a literature search. Twenty-five definitions and 31 measures were found. When applied to a general and a disease-specific quality of life questionnaire large variation in results was observed, partly explained by different goals of existing methods. Four major issues are considered to claim the usefulness of an evaluative health-related quality of life (HRQL) instrument. Their relation with responsiveness is discussed. The confusion about responsiveness arises mostly from a lack of distinction between cross-sectional and longitudinal validity and from a lack of distinction between responsiveness defined as the effect of treatment and responsiveness defined as the correlation of changes in the instrument with changes in other measures. All measures of what is currently called responsiveness can be looked at as measures of longitudinal validity or as measures of treatment effect. The latter ones tell us little about how well the instrument serves its purpose and are only of use in interpreting score changes. We therefore argue that the concept of responsiveness can be rejected as a separate measurement property of an evaluative instrument.

On assessing responsiveness of health-related quality of life instruments: guidelines for instrument evaluation.

Background Urinary incontinence (UI) is a common disorder that is increasingly important as our population ages. Less is known about UI in younger women, and few large surveys have been able to determine risk factors by linking their data to patients’ medical findings. Methods We conducted a population-based, age-stratified postal survey of 6000 women aged between 30 and 90 years who were enrolled in a large health maintenance organization in Washington State. Results The response rate was 64% (n = 3536) after exclusion criteria were applied. The population-based prevalence of UI was 45%. Prevalence increased with age, from 28% for 30- to 39-year-old women to 55% for 80- to 90-year-old women. Eighteen percent of respondents reported severe UI. The prevalence of severe UI also increased notably with age, from 8% for 30- to 39-year-old women to 33% for 80- to 90-year-old women. Older age, higher body mass index (BMI, calculated as weight in kilograms divided by the square of height in meters), greater medical comorbidity, current major depression, a history of hysterectomy, and parity increased the odds of having UI. Not being white and having had only cesarean deliveries decreased the odds of having UI. Major depression (odds ratio, 2.48; 95% confidence interval, 1.65-3.72) and obesity, defined as having a BMI of 30 or greater (odds ratio, 2.39; 95% confidence interval, 1.99-2.87), had the strongest association with UI. Among women with UI, age, BMI, medical comorbidity, current major depression, diabetes, a history of hysterectomy, and having had only cesarean deliveries were significantly associated with severe UI. Conclusions Urinary incontinence is highly prevalent in women across their adult life span, and its severity increases linearly with age. Age, BMI, race, medical comorbidity, current major depression, a history of hysterectomy, parity, and having only had cesarean deliveries are each independent factors significantly associated with the likelihood of having UI.

https://jamanetwork.com/journals/jamainternalmedicine/articlepdf/486453/ioi40612.pdf

Urinary Incontinence in US Women A Population-Based Study

Objective: This report extracts important considerations for determining and applying clinically significant differences in quality of life (QOL) measures from six published articles written by 30 international experts in the field of QOL assessment and evaluation. The original six articles were presented at the Symposium on Clinical Significance of Quality of Life Measures in Cancer Patients at the Mayo Clinic in April 2002 and subsequently were published in Mayo Clinic Proceedings. Principal findings: Specific examples and formulas are given for anchor-based methods, as well as distribution-based methods that correspond to known or relevant anchors to determine important differences in QOL measures. Important prerequisites for clinical significance associated with instrument selection, responsiveness, and the reporting of QOL trial results are provided. We also discuss estimating the number needed to treat (NNT) relative to clinically significant thresholds. Finally, we provide a rationale for applying group-derived standards to individual assessments. Conclusions: While no single method for determining clinical significance is unilaterally endorsed, the investigation and full reporting of multiple methods for establishing clinically significant change levels for a QOL measure, and greater direct involvement of clinicians in clinical significance studies are strongly encouraged.

I Yalcin

Papers

Quality of life of women with urinary incontinence: further development of the incontinence quality of life instrument (I-QOL)