Ken J. Beath

Associations Between Hearing Impairment and Mortality Risk in Older Persons: The Blue Mountains Hearing Study

PURPOSE To assess whether hearing loss predicts an increased risk of mortality. METHODS The Blue Mountains Hearing Study examined 2956 persons (49+ years) during 1997 to 2000. The Australian National Death Index was used to identify deaths until 2005. Hearing loss was defined as the pure-tone average (0.5-4 kHz) of air-conduction hearing thresholds greater than 25 dB HL. Associations between hearing loss and mortality risk were estimated using Cox regression and structural equation modeling (SEM). RESULTS When we used Cox regression, we discovered that hearing loss was associated with increased risk of cardiovascular (hazard ratio [HR] 1.36, 95% confidence interval [CI] 1.08-1.84) and all-cause (AC) mortality (HR 1.39, 95% CI 1.11-1.79) after adjustment for age and sex but not after multivariable adjustment. SEM pathway analysis, however, revealed a greater AC mortality risk (HR 2.58, 95% CI 1.64-4.05) in persons with hearing loss, which was mediated: cognitive impairment (HR 1.45, 95% CI 1.08-1.94) and walking disability (HR 1.63, 95% CI 1.24-2.15). These variables increased mortality both directly and indirectly through effects on self-rated health. CONCLUSIONS Hearing loss was associated with increased AC mortality via three mediating variables: disability in walking, cognitive impairment, and self-rated health. It is important to recognize that persons with combined disabilities are at increased risk of cardiovascular and AC mortality.

Direct and Indirect Effects of Visual Impairment on Mortality Risk in Older Persons: The Blue Mountains Eye Study

OBJECTIVE To investigate pathways from visual impairment to increased all-cause mortality in older persons. METHODS The Blue Mountains Eye Study examined 3654 persons 49 years and older (82.4% response) during 1992-1994 and after 5 and 10 years. Australian National Death Index data confirmed deaths until 2005. Visual impairment was defined as presenting, correctable, and noncorrectable, using better-eye visual acuity. Associations between visual impairment and mortality risk were estimated using Cox regression and structural equation modeling. RESULTS After 13 years, 1273 participants had died. Adjusting for mortality risk markers, higher mortality was associated with noncorrectable visual impairment (hazard ratio [HR], 1.35; 95% confidence interval [CI], 1.04-1.75). This association was stronger for ages younger than 75 years (HR, 2.58; 95% CI, 1.42-4.69). Structural equation modeling revealed greater effects of noncorrectable visual impairment on mortality risk (HR, 5.25; 95% CI, 1.97-14.01 for baseline ages <75 years), with both direct (HR, 2.16; 95% CI, 1.11-4.23) and indirect (HR, 2.43; 95% CI, 1.17-5.03) effects. Of mortality risk markers examined, only disability in walking demonstrated a significant indirect pathway for the link between visual impairment and mortality. CONCLUSIONS Visual impairment predicted mortality by both direct and indirect pathways, particularly for persons younger than 75 years with noncorrectable visual impairment. Disability in walking, which can substantially influence general health, represented a major indirect pathway.

Breast Implant-Associated Anaplastic Large Cell Lymphoma in Australia and New Zealand: High-Surface-Area Textured Implants Are Associated with Increased Risk.

Background: The association between breast implants and breast implant–associated anaplastic large cell lymphoma (ALCL) has been confirmed. Implant-related risk has been difficult to estimate to date due to incomplete datasets. Methods: All cases in Australia and New Zealand were identified and analyzed. Textured implants reported in this group were subjected to surface area analysis. Sales data from three leading breast implant manufacturers (i.e., Mentor, Allergan, and Silimed) dating back to 1999 were secured to estimate implant-specific risk. Results: Fifty-five cases of breast implant–associated ALCL were diagnosed in Australia and New Zealand between 2007 and 2016. The mean age of patients was 47.1 years and the mean time of implant exposure was 7.46 years. There were four deaths in the series related to mass and/or metastatic presentation. All patients were exposed to textured implants. Surface area analysis confirmed that higher surface area was associated with 64 of the 75 implants used (85.3 percent). Biocell salt loss textured (Allergan, Inamed, and McGhan) implants accounted for 58.7 percent of the implants used in this series. Comparative analysis showed the risk of developing breast implant–associated ALCL to be 14.11 times higher with Biocell textured implants and 10.84 higher with polyurethane (Silimed) textured implants compared with Siltex textured implants. Conclusions: This study has calculated implant-specific risk of breast implant–associated ALCL. Higher-surface-area textured implants have been shown to significantly increase the risk of breast implant–associated ALCL in Australia and New Zealand. The authors present a unifying hypothesis to explain these observations.

Short-term effects of a course of manual therapy and exercise in people with moderate chronic obstructive pulmonary disease: A preliminary clinical trial

OBJECTIVE The purpose of this preliminary study was to demonstrate the feasibility of a study that measures the short-term effects of a course of manual therapy (MT) and exercise (Ex) in people with moderate chronic obstructive pulmonary disease (COPD). METHODS Fifteen participants (9 males; mean age, 56.1 years), with moderate COPD (mean % predicted forced expiratory volume in the first second [FEV1% predicted], 61.8%), were randomly allocated to 1 of 3 groups: soft tissue therapy only (ST); ST and spinal manipulation (SM); or ST, SM, and Ex. The intervention continued for 4 weeks. Outcome measures included FEV1, forced vital capacity (FVC), chronic respiratory questionnaire (CRQ-SAS) scores, distance walked in a 6-minute walking test, and monitoring for adverse events. RESULTS There was an increase in FVC for the SM + ST + Ex group compared with ST only and ST + SM (1.01 and 1.00 L, respectively). Distance walked increased in the ST + SM and ST + SM + Ex groups compared with ST only (120.0 and 168.0 m, respectively). Dyspnea levels decreased in the ST + SM and ST + SM + Ex groups compared with ST only (0.64 and 0.44, respectively). There were no major or moderate adverse events reported following ST or SM interventions. CONCLUSIONS For this small group of patients, combining MT with Ex produced short improvements in FVC, distance walked, and dyspnea levels, with no major or moderate adverse events. This preliminary study showed that a larger study evaluating the clinical outcomes of MT for people with moderate COPD appears feasible.

A finite mixture method for outlier detection and robustness in meta‐analysis

When performing a meta-analysis unexplained variation above that predicted by within study variation is usually modeled by a random effect. However, in some cases, this is not sufficient to explain all the variation because of outlier or unusual studies. A previously described method is to define an outlier as a study requiring a higher random effects variance and testing each study sequentially. An extension is described where the studies are considered to be a finite mixture of outliers and non-outliers, allowing any number of outlier studies and the use of standard mixture model techniques. The bootstrap likelihood ratio test is used to determine if there are any outliers present by comparing models with and without outliers, and the outlier studies are identified using posterior predicted probabilities. The estimation of the overall treatment effect is then determined including all observations but with the outliers down-weighted. This has the advantage that studies that are marginal outliers are still included in the meta-analysis but with an appropriate weighting. The method is applied to examples from meta-analysis and meta-regression.

Is premigration health screening for tuberculosis worthwhile

Objective: To determine whether premigration screening for tuberculosis is worth undertaking in visa applicants, and whether screening resources are being appropriately directed towards intending migrants at highest risk of tuberculosis.

Medium term effects of including manual therapy in a pulmonary rehabilitation program for chronic obstructive pulmonary disease (COPD): a randomized controlled pilot trial.

Study design: Randomized clinical trial. Objective: To investigate the effect of including manual therapy (MT) in a pulmonary rehabilitation program for patients with chronic obstructive pulmonary disease (COPD). Background: The primary source of exercise limitation in people with COPD is dyspnea. The dyspnea is partly caused by changes in chest wall mechanics, with an increase in chest wall rigidity (CWR) contributing to a decrease in lung function. As MT is known to increase joint mobility, administering MT to people with COPD carries with it the potential to influence CWR and lung function. Methods: Thirty-three participants with COPD, aged between 55 and 70 years (mean = 65·5±4 years), were randomly assigned to three groups: pulmonary rehabilitation (PR) only, soft tissue therapy (ST) and PR, and ST, spinal manipulative therapy (SM), and PR. Outcome measures including forced expiratory volume in the 1st second (FEV1), forced vital capacity (FVC), 6-minute walking test (6MWT), St. Georges respiratory questionnaire (SGRQ), and the hospital anxiety and depression (HAD) scale were recorded at 0, 8, 16, and 24 weeks. Results: There was a significant difference in FVC between the three groups at 24 weeks (P = 0·04). For the ST+SM+PR group versus PR only the increase was 0·40 l (CI: 0·02, 0·79; P = 0·03). No major or moderate adverse events (AE) were reported following the administration of 131 ST and 272 SM interventions. Discussion: The increase in FVC is a unique finding. Although the underlying mechanisms responsible for this outcome are not yet understood, the most likely explanation is the synergistic effect resulting from the combination of interventions. These results support the call for a larger clinical trial in the use of MT for COPD.

Latent trajectory modelling of multivariate binary data

Latent trajectory analysis is a form of latent class analysis, where the manifest variables are longitudinal measurements of a single outcome. The latent classes may correspond to either constant increasing or decreasing levels of the outcome over time and describe different severity or course of a disease. Extension to multiple outcomes at each time point allows more accurate determination of classes, with classes based on combination of the outcomes, however requiring models which account for both correlation between outcomes and periods. Three models are described for multiple binary outcomes, observed at each time point: a latent class model where all outcomes are considered independent at all time points, a model incorporating random effects for subject only and one incorporating random effects for subject and period. The methods are applied to data on asthma and allergy symptoms in infants, with symptoms recorded at four time points, and it is shown that the incorporation of subject and period heterogeneity results in lower estimates of the number of latent classes.

Multilevel latent variable models for global health‐related quality of life assessment

Quality of life (QOL) assessment is a key component of many clinical studies and frequently requires the use of single global summary measures that capture the overall balance of findings from a potentially wide-ranging assessment of QOL issues. We propose and evaluate an irregular multilevel latent variable model suitable for use as a global summary tool for health-related QOL assessments. The proposed model is a multiple indicator and multiple cause style of model with a two-level latent variable structure. We approach the modeling from a general multilevel modeling perspective, using a combination of random and nonrandom cluster types to accommodate the mixture of issues commonly evaluated in health-related QOL assessments--overall perceptions of QOL and health, along with specific psychological, physical, social, and functional issues. Using clinical trial data, we evaluate the merits and application of this approach in detail, both for mean global QOL and for change from baseline. We show that the proposed model generally performs well in comparing global patterns of treatment effect and provides more precise and reliable estimates than several common alternatives such as selecting from or averaging observed global item measures. A variety of computational methods could be used for estimation. We derived a closed-form expression for the marginal likelihood that can be used to obtain maximum likelihood parameter estimates when normality assumptions are reasonable. Our approach is useful for QOL evaluations aimed at pharmacoeconomic or individual clinical decision making and in obtaining summary QOL measures for use in quality-adjusted survival analyses.

The specificity of the biosocial model to borderline traits

Background A number of theories have been proposed to account for the development of borderline personality disorder (BPD). The biosocial model considers emotional dysregulation to be central to the disorder, caused in turn by an emotionally vulnerable child being raised in an invalidating environment. This aetiological model is potentially too broad, as many of these constructs may be equally important to other mental health conditions, making the model non-specific to BPD. Method We sought to contrast the explanatory value of the constructs identified by the biosocial model of BPD to an alternate form of psychopathology (chronic worry), using a nonclinical sample (N = 271), via the completion of self-report questionnaires. Results Childhood emotional vulnerability had a similar relationship to chronic worry as to borderline traits, with emotional dysregulation playing an important role in both disorders. Contrary to the biosocial model′s predictions, the interaction effects between the childhood antecedents were not found to play an important role in either psychopathology. Conclusion The lack of an interaction effect between invalidating parenting and emotional vulnerability suggests that this aspect of the biosocial model may not be a strong predictor of BPD. Key elements of the biosocial model may have utility as more generic predictors of psychopathology.