Clinically important differences in health-related quality of life for patients with asthma: an expert consensus panel report

The influence of hospitalization or intensive care unit admission on declines in health-related quality of life

RATIONALE

Survivors of critical illness report impaired health-related quality of life (HRQoL) after hospital discharge, but the degree to which these impairments are attributable to critical illness is unknown.

OBJECTIVES

We sought to examine changes in HRQoL associated with an intensive care unit (ICU) stay and the differential association of type of hospitalization (critical illness versus noncritical illness) on changes in HRQoL.

METHODS

We identified 11,243 participants in the Ambulatory Care Quality Improvement Project (a multicenter randomized trial of Veterans conducted March 1997 to August 2000) completing at least two Medical Outcomes Study Short-Form 36 questionnaires over 2 years, and categorized patients by hospitalization status during the interval between measures. We used multiple linear regression with generalized estimating equations for analysis.

MEASUREMENTS AND MAIN RESULTS

Our primary outcome was change in the Physical Component Summary score. Participants requiring hospitalization or ICU admission had significantly worse baseline HRQoL than those not hospitalized (P < 0.001). Compared with patients who were not hospitalized, follow-up Physical Component Summary scores were lower among non-ICU hospitalized patients and ICU patients (adjusted β-coefficient = -1.40 [95% confidence interval, -1.81, -0.99] and adjusted β-coefficient = -1.53 [95% confidence interval, -2.11, -0.95], respectively), with no difference between the two groups (P value = 0.80). Similar results were seen for the Mental Component Summary score and each of the Medical Outcomes Study Short-Form 36 subdomains.

CONCLUSIONS

Prehospital HRQoL is a significant determinant of HRQoL after hospitalization or ICU admission. Hospitalization is associated with increased risk of impairment in HRQoL after discharge, yet the overall magnitude of this reduction is small and similar between non-ICU hospitalized and critically ill patients.

Irritable bowel syndrome: modern concepts and management options

Irritable bowel syndrome is the most common functional gastrointestinal disorder, manifesting as abdominal pain/discomfort and altered bowel function. Despite affecting as many as 20% of adults, a lack of understanding of etiopathogenesis and evaluation strategies results in diagnostic uncertainty, and in turn frustration of both the physician and the patient. This review summarizes the current literature on the diagnosis and management of irritable bowel syndrome, with attention to evidence-based approaches. A 4-step treatment strategy that has been used successfully in our tertiary referral practice is presented and should lead to successful therapeutic outcomes in the majority of patients with irritable bowel syndrome.

Relationship of type of work with health-related quality of life

PURPOSE

To examine the relation of work type with health-related quality of life (HRQoL) in healthy workers.

METHODS

We cross-sectionally examined 4427 (3605 men and 822 women) healthy workers in Japan, aged 19-69 years. We assessed HRQoL based on scores for five scales of the SF-36. Multiple regression was applied to examine the relation of work type (nighttime, shift, day to night, and daytime) with the five HRQoL norm-based scores, lower scores of which indicate poorer health status, adjusted for confounding factors, including sleeping duration.

RESULTS

Shiftwork was inversely related to role physical [regression estimate (β) = -2.12, 95 % confidence intervals (CI) -2.94, -1.30, P < 0.001], general health (β = -1.37, 95 % CI -2.01, -0.72, P < 0.001), role emotional (β = -1.24, 95% CI -1.98, -0.50, P < 0.001), and mental health (β = -1.31, 95% CI -2.01, -0.63, P < 0.001) independent of confounding factors, but not to vitality. Day-to-nighttime work was inversely related to all the five HRQoL subscales (Ps 0.012 to <0.001).

CONCLUSION

Shiftwork was significantly inversely related to four out of the five HRQoL, except for vitality, and day-to-nighttime work was significantly inversely related to all five HRQoL, independent of demographic and lifestyle factors.

A 12-month, moderate-intensity exercise training program improves fitness and quality of life in adults with asthma: a controlled trial

Background

Physical training has been shown to improve exercise capabilities in patients with asthma. Most studies focused on children and younger adults. Previously, the maximum program duration was six months. It is not known whether the same results may be obtained with lower intensity programs and sustained for time periods longer than 6 months. This controlled study was undertaken to investigate the effects of a moderate intensity outpatient training program of one year duration on physical fitness and quality of life in adults with asthma.

Methods

21 adult asthmatics (mean age 56 ± 10 years) were allocated to outpatient training (n = 13) or standard care (n = 8). Exercise consisted of once weekly, 60-minute sessions of moderate intensity. Assessments at baseline and after one year included cardiopulmonary exercise testing and Short Form-36 and Asthma Quality of Life Questionnaires.

Results

Following one year of exercise, relevant improvements were observed in the training group for maximum work capacity (p = 0.005), peak oxygen uptake (p < 0.005), O₂pulse (p < 0.05), maximum ventilation (p < 0.005), and most of the quality of life domains. No changes were observed in the control group.

Conclusions

A physiotherapist-led, long-term, moderate-intensity exercise program of one year duration can induce clinically relevant improvements in exercise capabilities and health-related quality of life in well-motivated adults with asthma.

Trial registration

clinicaltrials.gov NCT01097473. Date trial registered: 31.03.2010.

Methods for specifying the target difference in a randomised controlled trial: the Difference ELicitation in TriAls (DELTA) systematic review

BACKGROUND

Randomised controlled trials (RCTs) are widely accepted as the preferred study design for evaluating healthcare interventions. When the sample size is determined, a (target) difference is typically specified that the RCT is designed to detect. This provides reassurance that the study will be informative, i.e., should such a difference exist, it is likely to be detected with the required statistical precision. The aim of this review was to identify potential methods for specifying the target difference in an RCT sample size calculation.

METHODS AND FINDINGS

A comprehensive systematic review of medical and non-medical literature was carried out for methods that could be used to specify the target difference for an RCT sample size calculation. The databases searched were MEDLINE, MEDLINE In-Process, EMBASE, the Cochrane Central Register of Controlled Trials, the Cochrane Methodology Register, PsycINFO, Science Citation Index, EconLit, the Education Resources Information Center (ERIC), and Scopus (for in-press publications); the search period was from 1966 or the earliest date covered, to between November 2010 and January 2011. Additionally, textbooks addressing the methodology of clinical trials and International Conference on Harmonisation of Technical Requirements for Registration of Pharmaceuticals for Human Use (ICH) tripartite guidelines for clinical trials were also consulted. A narrative synthesis of methods was produced. Studies that described a method that could be used for specifying an important and/or realistic difference were included. The search identified 11,485 potentially relevant articles from the databases searched. Of these, 1,434 were selected for full-text assessment, and a further nine were identified from other sources. Fifteen clinical trial textbooks and the ICH tripartite guidelines were also reviewed. In total, 777 studies were included, and within them, seven methods were identified-anchor, distribution, health economic, opinion-seeking, pilot study, review of the evidence base, and standardised effect size.

CONCLUSIONS

A variety of methods are available that researchers can use for specifying the target difference in an RCT sample size calculation. Appropriate methods may vary depending on the aim (e.g., specifying an important difference versus a realistic difference), context (e.g., research question and availability of data), and underlying framework adopted (e.g., Bayesian versus conventional statistical approach). Guidance on the use of each method is given. No single method provides a perfect solution for all contexts.

Development of the Healthy Pathways Parent-Report Scales

PURPOSE

To describe the development of the Healthy Pathways Parent-Report Scales, measures of health, illness, well-being, and achievement among youth in middle childhood and adolescence.

METHODS

The Healthy Pathways Scales were derived from the Child Health and Illness Profile (CHIP) instruments. The CHIP domains of Comfort, Risk Avoidance, Satisfaction, and Resilience were modified to reflect advances in child health conceptualization. Classical test and modern psychometric analyses were conducted using data collected from 1,527 parents of children aged 9–14 years. Intra-class correlation and differential item functioning analyses were used to evaluate the extent of child–parent agreement on the Healthy Pathways Scales.

RESULTS

After minor revisions, 11 of the 12 scales were found to measure unidimensional parent-assessed outcomes comprehensively (full range of the latent trait) and efficiently (a minimal number of items). Scales were unbiased by age, gender, and geographic location. The construct validity of the scales was supported by their capacity to differentiate children with and without chronic illnesses and to detect expected age and gender differences. Child–parent agreement was poor to moderate at both the scale and item levels.

CONCLUSIONS

The Healthy Pathways Parent-Report Scales may be used to reliably, accurately, and efficiently assess unidimensional aspects of health, illness, well-being, and achievement in clinical and population-based research studies involving youth in middle childhood and adolescence.

Interpreting one oral health impact profile point

Background

Interpretation of scores from oral health-related quality of life (OHRQoL) instruments, such as the Oral Health Impact Profile (OHIP) is challenging. It was the aim of this study to determine how many oral impacts correspond to one point of the 49-item OHIP using a new approach which translates numeric problem counts into the traditionally used ordinal OHIP response categories.

Methods

A sample of 145 consecutively recruited prosthodontic patients seeking treatment or having a routine examination completed the German version of the 49-item OHIP with the original ordinal response format as a self-administered questionnaire. In addition, the numerical frequencies of impairment during the previous month were requested in personal interviews. Based on a multilevel mixed-effects linear regression, we estimated the mean difference with 95% confidence interval (CI) in numerical frequency between two adjacent ordinal responses.

Results

A numerical frequency of 15.2 (CI: 14.8 – 15.7) impacts per month corresponded to one OHIP point. This translates to approximately one impact every other day in the past month.

Conclusions

The oral problem count per day that corresponds to one OHIP-49 point can be used to interpret this instrument’s scores in cross-sectional and longitudinal studies. This number can help to better understand OHRQoL burden for patients, clinicians, and researchers alike.

Bridging the Gap: Using Triangulation Methodology to Estimate Minimal Clinically Important Differences (MCIDs)

This paper proposes the use of triangulation methodology to derive guidelines for interpreting change scores on health outcome measures. Triangulation integrates results from global ratings with clinical benchmarks of change, statistical estimates of magnitude, and qualitative data from patients and/or clinicians to derive guidelines that are not field-specific or method bound. A case study is presented to illustrate how this methodology can be applied. Secondary analyses were performed on blinded data from 2,971 patients enrolled in three phase IlIa clinical trials to develop guidelines for interpreting change scores on the Breathlessness Diary (BD), a relatively new approach for evaluating dyspnea outcomes in patients with chronic obstructive pulmonary disease. BD scores were examined by disease severity and rescue medication use. In addition, mean BD change scores by physician global ratings of efficacy were juxtaposed with changes in forced expiratory volume (FEV1) and St. George's Respiratory Questionnaire scores. Percent change, effect size, one-half standard deviation, and the standard error of measurement were used as statistical indicators of magnitude. Data from qualitative interviews provided insight into patient perspectives of change in dyspnea. Taking into consideration results across estimation methods, guidelines were developed for defining large, moderate, and small group-level mean changes on the BD. Areas of divergence and convergence across statistical indicators and clinical benchmarks in this case study highlight the importance of using triangulation methodology to derive guidelines that are both empirically sound and clinically relevant.

Interpreting clinical trial results of patient-perceived onset of effect in asthma: methods and results of a Delphi panel

OBJECTIVE

The purpose of this study was to determine if empirically observed differences in patient perception of, and satisfaction with, onset of effect between an active maintenance treatment and placebo are clinically meaningful to practicing clinicians. A secondary objective was to determine the lowest threshold for a clinically meaningful difference in terms of both between-group differences and maximum acceptable placebo effect.

METHODS

Twelve community-based healthcare professionals participated in a Delphi consensus panel. Panelists were provided with blinded results of two clinical trials showing statistically significant treatment effects for treatment A (budesonide/formoterol [Symbicort*]) over placebo in the proportion of patients who could perceive the medication working right away and the proportion of patients satisfied with this perception. Panelists were then asked to respond to a series of questions to identify a threshold for clinically important differences in patient-perceived onset of effect and satisfaction with speed of onset of effect. All expert panelists participated in two rounds of the Delphi process.

RESULTS

Panelists were unanimous in their conclusion that the statistically significant results from the two trials were clinically meaningful. According to these practitioners, the empirical results presented to them, showing that patients could feel a maintenance inhaler therapy work right away, were meaningful to clinical decision-making, and the attribute could potentially improve patient adherence with therapy. A group consensus was reached that a minimum active treatment response for these outcomes should range from 50% to 75% and be 2-3 times larger than the placebo response, with a maximum placebo effect of 26-40%.

CONCLUSION

A Delphi panel study of practitioners was used to establish a meaningful range of response and a minimal important difference for interpreting results of clinical trials in which patient perception of onset of effect and satisfaction with this perception are tested. While the views of this panel may not be generalized to the entire population of practitioners in the United States, results provide insight into how a typical practitioner is likely to view clinical trial results and how the information might be used in clinical practice.

An approach to define clinical significance in prosthodontics

PURPOSE

The concept of the minimal important difference (MID) of an oral health-related quality of life (OHRQoL) questionnaire has been proposed to refer to the smallest OHRQoL score difference considered to be clinically important in oral health. This study determined the MID for the 49-item Oral Health Impact Profile (OHIP) in prosthodontic patients. This could serve as a patient-based approach to define clinical significance for prosthodontic interventions.

MATERIALS AND METHODS

A consecutive sample of 224 adult patients completed the OHIP questionnaires twice before treatment was performed and 4 to 6 weeks after prosthodontic treatment was finished. At follow-up patients were asked about their overall impression of the treatment (global transition; answer categories "improved a lot,""improved a little,""stayed the same,""worsened a little," and "worsened a lot").

RESULTS

The median of baseline and follow-up differences in OHIP (change scores) was computed for subjects (N = 47) reporting a "little improvement." This figure was considered the MID for the OHIP, and it was found to be 6 OHIP units (95% confidence interval: 2 to 9).

CONCLUSION

The MID of the OHIP is an important benchmark to assess individual and group treatment effects in prosthodontics and could be used to approach what is clinically significant in terms of patient-based outcomes.

Inhaled mometasone furoate improves health-related quality of life in patients with persistent asthma

Results from two clinical trials of mometasone furoate administered via a dry powder inhaler (MF-DPI) were reviewed to evaluate the consistency of effects of MF-DPI administered once-daily in the evening (QD PM) or twice-daily (BID) on health-related quality of life (HRQOL) in adults with persistent asthma previously treated with inhaled corticosteroids. HRQOL data were collected from two 12-week, randomized, double-blind trials: in study 1 (n = 268), patients received MF-DPI 400 microg QD PM (1 inhalation), MF-DPI 200 microg BID, or placebo; in study 2 (n = 400), patients received MF-DPI 200 microg QD PM, MF-DPI 400 microg QD PM (1 inhalation), MF-DPI 200 microg BID, MF-DPI 400 microg QD PM (2 inhalations of 200 microg), or placebo. In both studies, HRQOL was assessed using the Medical Outcomes Survey 36-item Short Form (SF-36) and an asthma-specific module. MF-DPI was associated with consistent, statistically significant improvements in asthma-specific total scores, breathlessness, asthma concerns, and physical symptoms compared with placebo in both trials (p < 0.05 vs. placebo). MF-DPI improved SF-36 Physical Component Summary scores at all doses except 200 microg QD PM. In conclusion, the results from two placebo-controlled trials suggest that MF-DPI 400 microg/d, administered once or twice-daily, produces consistent, statistically, and clinically significant improvement in HRQOL measures in patients with persistent asthma.

A Randomized Clinical Trial of Aquatic versus Land Exercise to Improve Balance, Function, and Quality of Life in Older Women with Osteoporosis

PURPOSE

Despite the decreased gravitational loading that is experienced in an aquatic environment, little research has been conducted on this exercise medium for women with osteoporosis (OP). Aquatic exercise (AE) may improve function and balance, thus ultimately decreasing fall risk and the potential for hip fractures in this high-risk population.

METHOD

A total of 68 women with OP, aged 60 years or older, were recruited into a randomized clinical trial evaluating the impact of AE, land exercise (LE), and no exercise (NE) on balance, functional mobility, and quality of life (QOL).

RESULTS

Only one balance measure (backward tandem walk) significantly improved with AE compared to LE, but this did not translate into a greater improvement in self-report function. There were no significant differences between the exercise interventions and NE, except for in ratings of global change, where participants in the AE group were three times more likely to report improvement than those in the NE group.

CONCLUSION

There were no differences in balance, function, or QOL in women with OP who followed an AE or LE programme compared to those in an NE control group. However, the significant differences in backward tandem walk between the AE and LE groups and self-reported global change between the AE and NE groups warrant further investigation. Significant improvements in balance and global change suggest that AE is a viable alternative for older women with OP who have difficulty exercising on land.

Adolescent idiopathic scoliosis patients report increased pain at five years compared with two years after surgical treatment

STUDY DESIGN

A multicenter study of changes in Scoliosis Research Society (SRS) outcome measures after surgical treatment of adolescent idiopathic scoliosis (AIS).

OBJECTIVE

To evaluate changes in patient determined outcome measures between 2 and 5 years after AIS surgery.

SUMMARY OF BACKGROUND DATA

Current surgical procedures have been shown to improve subjective measures in patients with AIS. At 2-year follow-up, AIS patients reported significant improvement in all 4 preoperative domains of the SRS questionnaire. In addition, the major Cobb angle was shown to be negatively correlated with preoperative scores in the pain, general self-image, and general function domains. Five-year SRS scores have not been evaluated previously.

METHODS

A multicenter, prospectively generated database was used to obtain perioperative, radiographic, and SRS-24 outcomes data. The inclusion criteria were: a diagnosis of AIS, surgical treatment (anterior, posterior, or combined), a comprehensive set of radiographic measures, and completed preoperative, 2-year, and 5-year SRS questionnaires. Repeated measures analysis of variance was used to compare changes in patient responses for each of the 7 outcome domains. Univariate analysis of variance was used to compare the change in pain score at 5 years to the level of the lowest instrumented vertebrae and surgical approach. A correlation analysis was used to determine the association between changes in any of the radiographic variables and changes in SRS scores. The data were checked for normality and equal variances, and the level of significance was set at P < 0.01.

RESULTS

Forty-nine patients (42 women, 7 men; 14.2 +/- 2.1 year old; 5.4 +/- 0.6 years follow-up) met the inclusion criteria for this study. Thirty-seven of 49 (76%) of these patients underwent an open or thoracoscopic anterior procedure. SRS-24 scores improved significantly in 3 of the 4 preoperative domains at the 2-year visit. At 5 years postop, a statistically significant decrease in the pain score (4.2 +/- 0.6 to 3.9 +/- 0.9, P = 0.003) and a trend toward worsening scores in 4 other domains was observed; however, Patient Satisfaction scores remained unchanged. Lowest instrumented vertebrae and surgical approach could not be correlated to changes in the pain score. In addition, no correlation was found between changes in any of the 21 radiographic measures evaluated and changes in SRS scores.

CONCLUSION

There was a statistically significant increase in reported pain from 2 to 5 years after surgical treatment; however, the etiology of worsening pain scores could not be elucidated. Given continued patient satisfaction, the clinical relevance of this small reduction remains unknown. Nevertheless, this observation deserves further evaluation and must be considered in relation to the natural history of this disease.

Validity of patient-reported health-related quality of life global ratings of change using structural equation modeling

BACKGROUND

Patient-perceived global ratings of change are often used as anchors of health-related quality of life (HRQoL) since they are easy for clinicians to interpret and incorporate the patient's perception of change as a means to capture clinical significance. Although this approach may be preferred, the validity of the anchor-based approach is currently under scrutiny.

OBJECTIVE

To estimate the explained variation in single-item domain-specific global ratings of change (GRCs) that is accounted for by time 1 (T1) and time 2 (T2) domain-specific summary change scores from the Short-Form 36, V2 (SF-36) Health Survey in asthma primary care patients.

METHODS

The baseline and first follow-up enrollment data to be evaluated in this investigation were part of a larger longitudinal HRQoL study conducted from August 2000-December 2002, in which the 356 asthma patients from Midwestern primary care facilities completed telephone interviews for every two consecutive months for a year on multiple HRQoL measures, including the SF-36 and domain-specific GRCs. A structural equation modeling technique was employed to ascertain the explained variability in patient-reported GRCs for each SF-36 domain that is accounted for by the summary change scores at the two time-points for four SF-36 domains (bodily pain, general health perception, mental health, and physical functioning). The model was estimated by the maximum likelihood method with the Satorra-Bentler correction for ordinal variables using equal threshold asymptotic covariance matrices.

RESULTS

Multicollinearity between T1 and T2 latent constructs clouded interpretation of the standardized structural coefficients leading to GRCs. Correlations, however, revealed that all four domain-specific GRCs were more strongly related to T2- than T1-domain summary scores, indicating that patients were not equally relying on T1 and T2 to generate the GRCs. Furthermore, T1-domain summary scores were not of equal magnitude and opposite sign as compared to T2 scores.

CONCLUSIONS

In this study, there is insufficient evidence to establish SF-36 domain-specific GRC validity in asthma primary care patients. Therefore, it is recommended to reassess validity before using domain-specific SF-36 GRCs to classify clinically important change over time.

Improvement in quality of life with omalizumab in patients with severe allergic asthma

BACKGROUND

Patients with severe persistent asthma experience daily symptoms and frequent serious exacerbations that contribute to a significant impairment of health-related quality of life (QoL).

METHODS

A pooled analysis was completed of six controlled clinical trials that evaluated the effect of add-on omalizumab on asthma-related QoL in patients with severe persistent allergic (IgE-mediated) asthma. Asthma-related QoL was assessed at baseline and treatment endpoint using the well-validated Juniper Asthma Quality of Life Questionnaire (AQLQ). Change from baseline in AQLQ total score was compared between treatments using analysis of covariance methods. The percentage of patients who achieved a clinically meaningful (> or = 0.5-point) improvement in AQLQ total score was compared using the Mantel-Haenszel Chi-square test.

RESULTS

The pooled patient population comprised 2548 patients (omalizumab, n = 1342; control, n = 1206), of whom 96% had severe persistent asthma according to the GINA 2002 classification. Omalizumab produced significantly greater improvements in AQLQ total score vs the control group (mean increases of 1.01 and 0.61 points, respectively; p < 0.001). In addition, significantly more omalizumab-treated patients achieved a clinically meaningful improvement in AQLQ total score than patients in the control group (66.3% vs 52.4%; p < 0.001).

CONCLUSIONS

Add-on therapy with omalizumab improves QoL to a significant and clinically meaningful level in patients with severe persistent allergic asthma.

A comparison of traditional and Rasch cut points for assessing clinically important change in health-related quality of life among patients with asthma

BACKGROUND

Patient-perceived change in health-related quality of life (HRQoL) domains has often been classified using a 15-point patient transition rating scale. However, traditional change levels of trivial ( - 1, 0, or 1), minimal (2, 3 or - 2, - 3), moderate (4, 5 or - 4, - 5) and large (6, 7 or - 6, - 7) on this scale have been arbitrarily defined and originally assumed that change related to an improvement was the same as that for a decline.

OBJECTIVE

To compare traditional and Rasch partial credit model-derived cut points and the mean changes for each change categorization when assessing clinically important change in asthma-specific HRQoL.

METHODS

Our sample included 396 asthmatic outpatients who completed bimonthly telephone interviews on the Asthma Quality of Life Questionnaire and transition rating items over 1 year of participation. We employed item response theory in a novel approach to identify cut points on domain-specific HRQoL change data and transition ratings. After determining natural cut points for minimal, moderate, and large differences on the transition rating anchor, we calculated mean changes under change categorizations for both improvements and declines for the two transition rating classification approaches.

RESULTS

Although traditional and Rasch categorizations for small, moderate, and large changes slightly differed and displayed a lack of symmetry between improvements and declines, nearly all mean changes between classification approaches were comparable.

CONCLUSIONS

In this study, traditional transition rating cut points remain suitable to assess HRQoL clinical significance in outpatients with asthma.

Physician-estimated disease severity in patients with chronic heart or lung disease: a cross-sectional analysis

BACKGROUND

We evaluated how well physicians' global estimates of disease severity correspond to more specific physician-rated disease variables as well as patients' self-rated health and other patient variables.

METHODS

We analyzed baseline data from 1662 primary care patients with chronic cardiac or pulmonary disease who were enrolled in a longitudinal study of health-related quality of life (HRQoL). Each patient's primary physician rated overall disease severity, estimated the two-year risk of hospitalization and mortality, and reported the use of disease-specific medications, tests, and subspecialty referrals. Patient variables included sociodemographic characteristics, psychosocial factors, self-rated health, and both generic and disease-specific HRQoL.

RESULTS

Physicians rated 40% of their patients "about average", 30% "worse", and 30% "better" than the typical patient seen with the specific target disorder. The physician's global estimate of disease severity was strongly associated (P < 0.001) with each of the five more specific elements of physician-rated disease severity, but only marginally associated with patient self-rated health. Multivariable regression identified a set of patient variables that explained 16.4% of the variance in physician-rated disease severity.

CONCLUSION

Physicians' global ratings may provide disease severity and prognostic information unique from and complementary to patient self-rated health and HRQoL measures. The elements influencing physician-rated disease severity and its predictive validity for clinical outcomes warrant prospective investigation.

Interpreting quality-of-life data: methods for community consensus in asthma

BACKGROUND

Change in health-related quality of life (HRQoL) is an important outcome in asthma treatment. Patient and provider consensus on how to determine thresholds for identifying important improvements and declines, however, has not been achieved.

OBJECTIVE

To search for consensus in clinically important difference (CID) thresholds for HRQoL change from 3 points of view: (1) an expert panel of physicians who treat patients with asthma and measure the HRQoL of their patients, (2) asthmatic patients, and (3) the primary care physicians (PCPs) of these asthmatic patients.

METHODS

The expert panel used Delphi and consensus methods to agree on CID levels for the Asthma Quality of Life Questionnaire and the Medical Outcomes Study 36-Item Short-Form Health Survey, version 2.0. A total of 396 patients attending midwestern primary care clinic sites completed these interviews bimonthly for 1 year. The 46 PCPs treating these patients completed baseline assessments on each patient's asthma and then evaluated the change in each patient's condition at subsequent office visits during the next year.

RESULTS

The patient-perceived estimates were consistent with results of previous studies but were notably lower than those derived from the expert panel and the PCPs. The Short-Form Health Survey generally did not provide sufficient sensitivity to detect important changes.

CONCLUSIONS

Although consensus on the interpretation of change in HRQoL measures was not achieved, this evidence-based approach demonstrates the value of patient and physician perspectives and the need for improved dialogue and understanding to optimize the HRQoL of patients with asthma.

Study protocol: The Improving Care of Acute Lung Injury Patients (ICAP) study

INTRODUCTION

The short-term mortality benefit of lower tidal volume ventilation (LTVV) for patients with acute lung injury/acute respiratory distress syndrome (ALI/ARDS) has been demonstrated in a large, multi-center randomized trial. However, the impact of LTVV and other critical care therapies on the longer-term outcomes of ALI/ARDS survivors remains uncertain. The Improving Care of ALI Patients (ICAP) study is a multi-site, prospective cohort study that aims to evaluate the longer-term outcomes of ALI/ARDS survivors with a particular focus on the effect of LTVV and other critical care therapies.

METHODS

Consecutive mechanically ventilated ALI/ARDS patients from 11 intensive care units (ICUs) at four hospitals in the city of Baltimore, MD, USA, will be enrolled in a prospective cohort study. Exposures (patient-based, clinical management, and ICU organizational) will be comprehensively collected both at baseline and throughout patients' ICU stay. Outcomes, including mortality, organ impairment, functional status, and quality of life, will be assessed with the use of standardized surveys and testing at 3, 6, 12, and 24 months after ALI/ARDS diagnosis. A multi-faceted retention strategy will be used to minimize participant loss to follow-up.

RESULTS

On the basis of the historical incidence of ALI/ARDS at the study sites, we expect to enroll 520 patients over two years. This projected sample size is more than double that of any published study of long-term outcomes in ALI/ARDS survivors, providing 86% power to detect a relative mortality hazard of 0.70 in patients receiving higher versus lower exposure to LTVV. The projected sample size also provides sufficient power to evaluate the association between a variety of other exposure and outcome variables, including quality of life.

CONCLUSION

The ICAP study is a novel, prospective cohort study that will build on previous critical care research to improve our understanding of the longer-term impact of ALI/ARDS, LTVV and other aspects of critical care management. Given the paucity of information about the impact of interventions on long-term outcomes for survivors of critical illness, this study can provide important information to inform clinical practice.

Immunotherapy with depigmented glutaraldehyde-polymerized extracts: changes in quality of life

BACKGROUND

Immunotherapy (IT) with modified allergens reduces allergic rhinitis (AR) symptoms and medications requirements. Improvement of quality of life (QOL) is a key point in the treatment of AR. The aim of this study was to provide evidence of changes related to the patient's QOL (well-being) induced by a modified (depigmented glutaraldehyde-polymerized) therapeutic vaccine and of its safety.

MATERIAL AND METHODS

Fifty-three patients with a well-documented clinical history of seasonal AR sensitized to Dactylis glomerata and Olea europaea pollens were included in a randomized clinical trial. Twenty-five patients (Group-A) received a mixture of D. glomerata and O. europaea pollen extracts and 28 patients received placebo (group-C). Any adverse event was recorded and graded in accordance with EAACI guidelines. RQLQ was recorded before the treatment (pollen season 2000) and after 1 year of treatment (pollen season 2001). Dose-response skin prick test with each allergen extract was conducted at baseline and at the end of the study.

RESULTS

Each patient received 17 injections during this period. All patients completed the trial and no systemic adverse reactions were recorded. Symptom scores (P<0.001) and medication requirements (P<0.001) were significantly reduced in the IT group during the pollen season. This patient group also experienced greater and statistically significant improvement in overall RQLQ score and in five of the seven domains, all of them surpassing the threshold of 'minimal important difference' of 0.5 points.

CONCLUSIONS

Results of this study provided evidence that IT with depigmented, glutaraldehyde-modified allergen extracts was well-tolerated and added beneficial effects to AR treatment in pollen allergic patients eliciting an improvement in QOL enough to justify a change in the patient's treatment.

Sufficiently Important Difference: Expanding the Framework of Clinical Significance

Background. It is generally agreed that randomized controlled trials should be powered to detect small but clinically significant treatment effects. Toward these ends, minimal important difference (MID) was proposed as a benchmark for designing trials and for interpreting health-related quality-of-life instrument scores. MID was defined in 1989 as “the smallest difference in score in the domain of interest which patients perceive as beneficial and which would mandate, in the absence of troubling side effects and excessive cost, a change in the patient’s management.” Objective. 1) To expand the idea of minimal clinically important difference so as to take into account harms as well as benefits. 2) To propose concepts and methods with which to do so. Summary. The authors define sufficiently important difference (SID) as the smallest amount of patient-valued benefit that an intervention would require to justify associated costs, risks, and other harms. As a means toward estimation of SID, the authors propose benefit-harm tradeoff methods, in which domains of benefit and harm are systematically traded off against each other and assessed in relation to the global decision of whether a treatment choice is worthwhile. Specific SID estimates can be used to power and interpret clinical trials or to inform health services research and/or public health policy. This article briefly describes the evolution of the important difference concept and outlines similarities and differences between MID and SID.

The use of patient reported outcome measures in routine clinical practice: lack of impact or lack of theory?

This paper applies a theory-driven approach to explore why the use of patient-reported outcome (PRO) measures in clinical practice, in particular, health-related quality of life (HRQoL) instruments, has little or no apparent influence on clinical decision making. A theory-driven approach involves combining knowledge of whether and how an intervention works. It is argued that such an approach is currently lacking within the literature evaluating the effectiveness of feeding back HRQoL information to clinicians. The paper identifies a number of mechanisms that might give rise to the expected outcomes that are currently implicit within the design of the intervention and hypotheses specified within the trials evaluating the use of HRQoL measures in clinical practice. It then examines how far current clinical practice matches these mechanisms and in doing so, a number of possible explanations for the lack of impact of HRQoL on clinical decision making are reviewed. The influence of HRQoL information on clinical decision making depends on a large number of factors related to the design of the intervention, patients' and clinicians' desire to discuss HRQoL issues within the consultation and the legitimacy that clinicians give to HRQoL instruments. To date, knowledge of how the feedback of HRQoL information to clinicians might improve doctor-patient communication or clinical decision making has yet to sufficiently inform an assessment of whether these aspects of patient care are improved. The paper concludes by specifying how the feedback of HRQoL information to clinicians might be modified to maximise its impact on clinical decision making.

A comparison of clinically important differences in health-related quality of life for patients with chronic lung disease, asthma, or heart disease

OBJECTIVE

On the eight scales of the Medical Outcomes Study Short-Form 36-Item Health Survey (SF-36), Version 2, we compared the clinically important difference (CID) thresholds for change over time developed by three separate expert panels of physicians with experience in quality of life assessment among patients with chronic obstructive pulmonary disease (COPD), asthma, and heart disease.

STUDY DESIGN

We used a modified Delphi technique combined with a face-to-face panel meeting within each disease to organize and conduct the consensus process among the expert panelists, who were familiar with the assessment and evaluations of health-related quality of life (HRQL) measures among patients with the panel-specific disease.

PRINCIPAL FINDINGS

Each of the expert panels first determined the magnitude of the smallest numerically possible change on each SF-36 scale, referred to as a state change, and then built their CIDs from this metric. All three panels attained consensus on the scale changes that constituted small, moderate, and large clinically important SF-36 change scores. The CIDs established by the heart disease panel were generally greater than the CIDs agreed on by the asthma and COPD panels.

CONCLUSIONS

These panel-derived thresholds reflect possible differences in disease management among the represented panel-specific diseases, and are all greater than the minimal CID thresholds previously developed for the SF-36 scales among patients with arthritis. If confirmed among patients with the relevant diseases and those patients' physicians, these disease-specific CIDs could assist both researchers and practicing clinicians in the use and interpretation of HRQL changes over time.

An introduction to medical statistics for health care professionals: Hypothesis tests and estimation

This article is the second in a series of three that will give health care professionals (HCPs) a sound introduction to medical statistics (Thomas, 2004). The objective of research is to find out about the population at large. However, it is generally not possible to study the whole of the population and research questions are addressed in an appropriate study sample. The next crucial step is then to use the information from the sample of individuals to make statements about the wider population of like individuals. This procedure of drawing conclusions about the population, based on study data, is known as inferential statistics. The findings from the study give us the best estimate of what is true for the relevant population, given the sample is representative of the population. It is important to consider how accurate this best estimate is, based on a single sample, when compared to the unknown population figure. Any difference between the observed sample result and the population characteristic is termed the sampling error. This article will cover the two main forms of statistical inference (hypothesis tests and estimation) along with issues that need to be addressed when considering the implications of the study results.

Test-retest reliability of the Mirowsky-Ross 2 x 2 Index of the Sense of Control

This study investigated the short-term stability of the 1991 Mirowsky-Ross 2 x 2 Index of the Sense of Control. From an ongoing longitudinal study, 304 subjects were randomly selected for test-retest interviews occurring 1 to 4 days after their regularly scheduled first follow-up interview. Test-retest reliability was assessed at the item level using percent agreement and weighted kappa. At the scale score level, reliability was assessed with the intraclass correlation coefficient (ICC). ICCs were also calculated within categories of demographic, socioeconomic, psychosocial, and functional status characteristics. There was moderate to substantial item-level agreement (mean weighted kappa = 51; weighted kappa range = .38 to .66). At the scale score level there was substantial agreement (ICC = .71). No appreciable differences in ICC values were found in the demographic, socioeconomic, psychosocial, and functional comparisons of status characteristics. Thus, this sense of control measure has acceptable test-retest reliability and is appropriate for use in longitudinal research.