The Importance of the Normality Assumption in Large Public Health Data Sets

Lumley, Thomas; Diehr, Paula; Emerson, Scott S.; Chen, Lu

doi:10.1146/annurev.publhealth.23.100901.140546

Cited by 1,301 publications

(949 citation statements)

References 22 publications

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“…No colinearity or interaction was found with regard to the variables. For all of the analyses, robust estimates were used to account for influential outliers or non-constant variance (Lumley et al 2002).…”

Section: Resultsmentioning

confidence: 99%

Interleukin-6 predicts short-term global functional decline in the oldest old: results from the BELFRAIL study

Adriaensen

Matheï

Vaes

et al. 2014

AGE

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The chronic inflammatory state at old age may contribute to the pathophysiology of or reflect chronic conditions resulting in loss of physical and mental functioning. Therefore, our objective was to examine the predictive value of a large battery of serum inflammatory markers as risk indicators for global functional decline and its specific physical and mental determinants in the oldest old. Global functional decline and specific aspects of physical and mental functional decline were assessed during an average of 1.66 years (±0.21) in a sample of 303 persons aged 80 years or older of the BELFRAIL study. Serum levels of 14 inflammatory proteins, including cytokines, growth factors, and acute phase proteins, were measured at baseline. Almost 20 % of the participants had a significant global functional decline over time. Interleukin (IL)-6 serum levels were uniquely positively associated with global functional decline, even after correcting for multiple confounders (odds ratio 1.51). Odds ratios for the individual aspects (physical dependency, physical performance, cognition, and depression) of functioning were lower, and composite scores of physical or mental decline were not significant. The proportion of global functional decline exhibited a dose-response curve with increasing levels of IL-6. Thus, IL-6 is an independent risk indicator for accelerated global functional decline in the oldest old. Our results suggest that simple serum levels of IL-6 may be very useful in short-term identification or evaluation of global functional status in the oldest old.

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Section: Resultsmentioning

confidence: 99%

Interleukin-6 predicts short-term global functional decline in the oldest old: results from the BELFRAIL study

Adriaensen

Matheï

Vaes

et al. 2014

AGE

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“…The serum levels of the immune markers were entered into the logistic models as tertiles. For all of the analyses, robust estimates were used due to the nonconstant variance (Lumley et al 2002).…”

Section: Resultsmentioning

confidence: 99%

Significance of serum immune markers in identification of global functional impairment in the oldest old: cross-sectional results from the BELFRAIL study

Adriaensen

Matheï

Pottelbergh

et al. 2013

AGE

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The large burden and coexistence of physical disability, cognitive impairment, and depression in the oldest old makes summary markers of global functioning of great value, allowing for risk stratification. Inflammation may be a common underlying cause or represents a final common pathway. The present study investigated the association between elevated serum inflammatory markers and global functioning and its underlying aspects. A representative sample of 415 communitydwelling elderly subjects participating in the BELFRAIL study, with a mean age of 85 years, was included in the present analysis. Data on physical performance, dependence, and mental aspects of functioning and serum levels of 15 inflammatory proteins, including cytokines, chemokines, and acute-phase proteins, were assessed. Interleukin (IL)-6 was negatively associated with global functioning (odds ratio (OR) 4.35). The odds ratios for C-reactive protein (CRP) (OR 2.37) and the combined score of IL-6 and CRP (OR 2.59) were lower or not significant. IL-6 was significantly associated with physical dependence and cognitive function, and only a highly elevated serum level was associated with physical performance. Physical dependence was associated with a highly elevated CRP serum level. The proportion of functionally impaired older persons with elevated IL-6 was 81.93 %, giving a low positive predictive value (0.38), but a high negative predictive value (0.87). So, IL-6 is strongly associated with global functioning and all of the individual aspects of functioning, except suspected depression, in communitydwelling persons 80 years and older.

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“…Based on the large sample size, we assumed normality [14] and used parametric statistical tests. We decided, a priori, that a difference of 10% between the NHDS and NIS was meaningful.…”

Section: Methodsmentioning

confidence: 99%

The National Hospital Discharge Survey and Nationwide Inpatient Sample: The Databases Used Affect Results in THA Research

Bekkers

Bot

Makarawung

et al. 2014

Clinical Orthopaedics &Amp; Related Research

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Background The National Hospital Discharge Survey (NHDS) and the Nationwide Inpatient Sample (NIS) collect sample data and publish annual estimates of inpatient care in the United States, and both are commonly used in orthopaedic research. However, there are important differences between the databases, and because of these differences, asking these two databases the same question may result in different answers. The degree to which this is true for arthroplasty-related research has, to our knowledge, not been characterized. Question/purposes We tested the following null hypotheses: (1) there are no differences between the NHDS and NIS in patient characteristics, comorbidities, and adverse events in patients with hip osteoarthritis treated with THA, and (2) there are no differences between databases in factors associated with inpatient mortality, adverse events, and length of hospital stay after THA. Methods The NHDS and NIS databases use different methods of data collection and weighting to provide data representative of all nonfederal hospital discharges in the United States. In 2006 the NHDS database contained 203,149 patients with hip arthritis treated with hip arthroplasty, and the NIS database included 193,879 patients. Multivariable analyses for factors associated with inpatient mortality, adverse events, and days of care were constructed for each database. Results We found that 26 of 42 of the factors in demographics, comorbidities, and adverse events after THA in the NIS and NHDS databases differed more than 10%. Age and days of care were associated with inpatient mortality with the NHDS and the NIS although the effect rates differ more than 10%. The NIS identified seven other factors not identified by the NHDS: wound complications, congestive heart failure, new mental disorder, chronic pulmonary disease, dementia, geographic region Northeast, acute postoperative anemia, and sex, that were associated with inpatient mortality even after controlling for potentially confounding variables. For inpatient adverse events, atrial fibrillation, osteoporosis, and female sex were associated with the NHDS and the NIS although the effect rates differ One of the authors (SB) certifies that he or she has received, during the study period, funding from VU University Amsterdam, faculty fund. One of the authors (AGJB) certifies that he or she has received, during the study period, funding from an AnnaFonds Travel grant (Dutch Orthopaedic travel grant) (less than USD 10,000), VSB-fonds, a nonmedical study grant (USD 10,000 to USD 100,000) and Prins Bernhard Cultuurfonds, Banning-de Jong fonds, a nonmedical study grant for excellent Dutch students USD 10,000 to USD 100,000). One of the authors (DR) certifies that he or she, or a member of his or her immediate family, has received or may receive payments or benefits, during the study period, an amount of USD (less than USD 10,000), from Wright Medical Technologies, Inc (Arlington, TN, USA), Biomet, Inc (Warsaw, IN, USA), Skeletal Dynamics Inc (Miami, FL, USA), AO Nor...

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The Importance of the Normality Assumption in Large Public Health Data Sets

Cited by 1,301 publications

References 22 publications

Interleukin-6 predicts short-term global functional decline in the oldest old: results from the BELFRAIL study

Interleukin-6 predicts short-term global functional decline in the oldest old: results from the BELFRAIL study

Significance of serum immune markers in identification of global functional impairment in the oldest old: cross-sectional results from the BELFRAIL study

The National Hospital Discharge Survey and Nationwide Inpatient Sample: The Databases Used Affect Results in THA Research

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