The Usefulness of Maximum Daily Temperatures Versus Defined Heatwave Periods in Assessing the Impact of Extreme Heat on ED Admissions for Chronic Conditions
Pages 80-89
Richard J. Woodman and Lidia Mayner
DOI: http://dx.doi.org/10.6000/1929-6029.2016.05.02.2
Published: 02 June 2016

Abstract: Objective: To compare a heatwave based exposure classification with a maximum daily temperature based exposure classification in assessing the associations between increased heat and emergency department (ED) admissions for chronic conditions.

Methods: ED admission data was collected from 4 public hospitals in South Australia from 2007 to 2009. Effects of 5 heatwave periods were examined using conditional logistic regression (heatwave versus non-heatwave) whilst effects of maximum daily temperature were explored using negative binomial regression with temperature classified using <25 °C (reference category) and additional 5 °C increments. Non-linear regression (ED admissions per unit °C) was used to examine possible temperature thresholds for increased ED admissions.

Results: In heatwave/non-heatwave analysis, an increased odds of admission during heatwaves was observed for heat-related complaints [OR=3.2; 95%CI=2.5, 4.11] and renal conditions [OR=1.13; 95%CI=1.05, 1.21] only. In temperature based analysis, mental health related conditions began increasing at 30-34 °C compared to <25 °C [IRR=1.11; 95%CI=1.02, 1.20], heat related conditions were increased at 35-39 °C [IRR=3.4; 95%CI=2.48, 4.64] while CVD admissions were lower above 40 °C [IRR=0.89; 95%CI=0.80-0.99]. Significant threshold temperatures were identified for heat-related conditions at 37.6 °C [p<0.001] and for renal admissions at 39.2 °C [p<0.001].

Conclusions: Using maximum daily temperature was a more sensitive approach to detecting effects of heat on ED admissions for chronic disease and also allowed the detection of temperature threshold effects. Assessing the impact of temperature rather than heatwaves should better identify the weather conditions that increase the risk of events amongst individuals with specific chronic conditions.

Time Profile of Time-Dependent Area Under the ROC Curve for Survival Data
Pages 103-113
J. Lambert, R. Porcher and S. Chevret
DOI: http://dx.doi.org/10.6000/1929-6029.2015.04.01.12
Published: 27 January 2015

Abstract:  In the setting of survival analysis, the time-dependent area under the receiver operating characteristic curve (AUC) has been proposed as a discrimination measure of interest. In contrast with the diagnostic setting, the definitions of time-dependent sensitivity and specificity are required. This paper evaluates the time-dependent profile of the resulting AUC(t), which has not been previously assessed. We show that, even when the effect of a binary biomarker on the hazard rate is constant, the value of AUC(t) varies over time according to the prevalence of the marker. The Time-profile of the continuous biomarker is illustrated with numerical integration, and data on several prognostic factors in AML are examined.

The Validity of Disease-Specific Quality of Life Attributions Among Adults with Multiple Chronic Conditions
Pages 17-40
John E. Ware Jr., Barbara Gandek and Jeroan Allison
DOI: http://dx.doi.org/10.6000/1929-6029.2016.05.01.3
Published: 08 January 2016

Abstract: Background: A crucial assumption underlying all disease-specific quality of life (QOL) measures, that patients can validly differentiate a specific disease in the presence of multiple chronic conditions, has not been tested using multiple methods. Our objective was to evaluate the convergent and discriminant validity of QOL attributions to specific diseases among adults with multiple chronic conditions (MCC).

Methods: Adults age 18 and older (N=4,480) sampled from eight pre-identified condition groups (asthma, COPD, angina/MI with angina, congestive heart failure, diabetes, chronic kidney disease, osteoarthritis, rheumatoid arthritis) completed an Internet survey. Comorbid conditions were determined using a 35-condition checklist. Product-moment correlations were analyzed separately by pre-identified condition group using the multitrait-multimethod of construct validation, where traits were defined by 9-26 conditions and each condition was measured by two methods: disease severity rating and Disease-specific Quality of Life Impact Scale (QDIS) global rating. A third method (symptom or clinical marker) was available for the eight pre-identified conditions. Convergent validity was supported when correlations among different methods of measuring the same condition (trait) were substantial (r≥ 0.40). Discriminant validity was supported when correlations between the same and different methods of measuring different conditions were significantly lower than corresponding convergent correlations.

Results: In support of convergent validity, 22 of 24 convergent correlations were substantial (r=0.38-0.84, median=0.53). In support of discriminant validity, 833 of 924 tests (90.2%) yielded significantly higher convergent than discriminant correlations across the eight pre-identified conditions. Exceptions to this pattern of results were most often observed for comorbid conditions within the same clinical area.

Conclusions: Collectively, convergent and discriminant test results support the construct validity of disease-specific QOL impact attributions across MCC within the eight pre-identified conditions. Noteworthy exceptions should be considered when interpreting some specific QOL impact attributions and warrant further study. Pursuit of a summary disease-specific QOL impact score standardized across MCC is recommended.

Total Hip and Knee Replacement in Eastern Libya: A Post-Conflict Case Series
Pages 291-297
Eman Elzwai, Rasha Elhnid, Zuhir Bodalal, Mustafa El Fadli and Salem Langhi
DOI: http://dx.doi.org/10.6000/1929-6029.2014.03.03.8
Published: 05 August 2014

Abstract: Background: Total knee replacement (TKR) and total hip replacement (THR) are effective procedures for alleviating pain and improving hip and knee function. Literature has not covered the experience of developing countries with arthroplasty – especially in an unstable post-conflict setting.

Methods: Patient records were obtained from a major surgical center in Benghazi where total joint arthroplasties (TJA) are performed for a period of twenty months and key parameters were analyzed. The patients were followed up on an outpatient basis at regular time intervals (one week, one month, three months and six months) and any complications were documented.

Results: A total of 135 total knee (81.5%, n=110) and total hip (18.5%, n=25) replacements were done in Benghazi mostly on elderly (mean age=60.2 years) females (72.2%, n=100). The most common causative pathology in both groups was osteoarthritis (80.6%, n=108). The most common complication was superficial infection (4.4%, n=6) by Staph aureus. The Harris Hip Score and Knee Society Score were used to determine the functional outcomes of THR and TKR respectively – both showing high values. The Short form 36 (SF36) health survey was carried out to assess the patients' satisfaction levels. For all the axes, the obtained score was over 80%.

Discussions: THR and TKR are major orthopedic surgeries that constitute an advancement in the treatment of chronic joint pain. Most of the demographic features of our patients match up well with previous literature – with certain exceptions. There was no difference in thromboembolic incidence between the group of patients who received LMWH and those who simply started early mobilization and physiotherapy. Despite a number of hindrances faced by the hospital due to the conflict (i.e. funding limitations and drug shortages), a low rate of complications was maintained. No thromboembolic incidents or mortalities occurred.

Conclusions: Libyan surgeons have had a good experience with TJA and patients have been satisfied with the outcomes.