Jason Gurney

Cancer-specific administrative data–based comorbidity indices provided valid alternative to Charlson and National Cancer Institute Indices

OBJECTIVE We aimed to develop and validate administrative data-based comorbidity indices for a range of cancer types that included all relevant concomitant conditions. STUDY DESIGN AND SETTINGS Patients diagnosed with colorectal, breast, gynecological, upper gastrointestinal, or urological cancers identified from the National Cancer Registry between July 1, 2006 and June 30, 2008 for the development cohort (n=14,096) and July 1, 2008 to December 31, 2009 for the validation cohort (n=11,014) were identified. A total of 50 conditions were identified using hospital discharge data before cancer diagnosis. Five site-specific indices and a combined site index were developed, with conditions weighted according to their log hazard ratios from age- and stage-adjusted Cox regression models with noncancer death as the outcome. We compared the performance of these indices (the C3 indices) with the Charlson and National Cancer Institute (NCI) comorbidity indices. RESULTS The correlation between the Charlson and C3 index scores ranged between 0.61 and 0.78. The C3 index outperformed the Charlson and NCI indices for all sites combined, colorectal, and upper gastrointestinal cancer, performing similarly for urological, breast, and gynecological cancers. CONCLUSION The C3 indices provide a valid alternative to measuring comorbidity in cancer populations, in some cases providing a modest improvement over other indices.

Identifying important comorbidity among cancer populations using administrative data: Prevalence and impact on survival.

Our study sought to optimize the identification and investigate the impact of comorbidity in cancer patients using routinely collected hospitalization data.

The impact of patient comorbidity on cancer stage at diagnosis

Background:It is known that cancer stage is affected by comorbidity, but the evidence regarding the magnitude and even direction of this effect is highly inconsistent and poorly understood. The aims of this study were to establish the impact of comorbidity on cancer stage at diagnosis, using both specific individual comorbid conditions and a global measure of comorbidity; and to assess whether this impact varied by cancer site, level of comorbidity burden and individual comorbidity type.Methods:We examined comorbidity among 14 096 patients with breast, colon, rectal, liver, stomach, ovarian, uterine, bladder or kidney cancer. Patients were identified from cancer registry data, and then linked to hospitalisation data to determine the presence of comorbidity in the 5 years preceding cancer diagnosis. Individual comorbid conditions were identified using ICD-10 codes, and overall burden of comorbidity attributed using a cancer-specific measure of comorbidity (C3 Index).Results:We observed that the presence of patient comorbidity (a) increases the odds of being diagnosed with distant metastases, (b) does not lead to earlier diagnosis and (c) increases the likelihood of a patient receiving no stage of disease at diagnosis.Conclusions:Patient comorbidity has a substantial impact on cancer stage at diagnosis; however, this impact varies considerably by cancer type, individual comorbid condition and overall comorbidity burden.

Development of a pharmacy-based comorbidity index for patients with cancer.

Objective:We aimed to develop and validate a pharmacy-based instrument to measure comorbidity among cancer patients. Methods:Patients diagnosed with colorectal, breast, gynecologic, stomach/liver, or renal/bladder cancers were identified from the New Zealand Cancer Registry between July 2006 and June 2008 for a development cohort (n=14096) and from July 2008 to December 2009 for a validation cohort (n=11014). Nineteen conditions were identified using community pharmaceutical data collected in the year before cancer diagnosis; 10 conditions were validated against hospital record data. A pharmacy-based comorbidity index (PBCI) was developed with each identified condition weighted according to their log hazard ratios from age-adjusted and stage-adjusted Cox regression models with noncancer death as the outcome. For each individual the weights were summed to give a score. Predictive abilities of PBCI were compared with the Charlson and C3 (hospitalization-based) comorbidity indices. Results:Kappa coefficients for conditions identified in notes review compared with pharmaceutical data ranged from 0.83 (diabetes) to 0.26 (anxiety/depression). Correlation coefficients with the Charlson ranged from 0.37 to 0.45 across cancers. All comorbidity indices were significant predictors of mortality, and differences between models were small. The PBCI generally performed as well or better than the Charlson index for predicting noncancer death within all cancer sites and slightly outperformed other indices in predicting noncancer mortality for breast cancer. Conclusions:The PBCI provides a valid alternative to measuring comorbidity in cancer patients. Researchers can use either hospitalization-based or pharmacy-based comorbidity measures for risk adjustment purposes.

A retrospective cohort study of patients with stomach and liver cancers: the impact of comorbidity and ethnicity on cancer care and outcomes

BackgroundComorbidity has an adverse impact on cancer survival partly through its negative impact on receipt of curative treatment. Comorbidity is unevenly distributed within populations, with some ethnic and socioeconomic groups having considerably higher burden. The aim of this study was to investigate the inter-relationships between comorbidity, ethnicity, receipt of treatment, and cancer survival among patients with stomach and liver cancer in New Zealand.MethodsUsing the New Zealand Cancer Registry, Māori patients diagnosed with stomach and liver cancers were identified (n = 269), and compared with a randomly selected group of non-Māori patients (n = 255). Clinical and outcome data were collected from medical records, and the administrative hospitalisation and mortality databases. Logistic and Cox regression modelling with multivariable adjustment were used to examine the impacts of ethnicity and comorbidity on receipt of treatment, and the impact of these variables on all-cause and cancer specific survival.ResultsMore than 70% of patients had died by two years post-diagnosis. As comorbidity burden increased among those with Stage I-III disease, the likelihood that the patient would receive curative surgery decreased (e.g. C3 Index score 6 vs 0, adjusted OR: 0.32, 95% CI 0.13-0.78) and risk of mortality increased (e.g. C3 Index score 6 vs 0, adjusted all-cause HR: 1.44, 95% CI 0.93-2.23). Receipt of curative surgery reduced this excess mortality, in some cases substantially; but the extent to which this occurred varied by level of comorbidity. Māori patients had somewhat higher levels of comorbidity (34% in highest comorbidity category compared with 23% for non-Māori) and poorer survival that was not explained by age, sex, site, stage, comorbidity or receipt of curative surgery (adjusted cancer-specific HR: 1.36, 95% CI 0.97-1.90; adjusted all-cause HR: 1.33, 95% CI 0.97-1.82). Access to healthcare factors accounted for 25-36% of this survival difference.ConclusionsPatients with comorbidity were substantially less likely to receive curative surgery and more likely to die than those without comorbidity. Receipt of curative surgery markedly reduced their excess mortality. Despite no discernible difference in likelihood of curative treatment receipt, Māori remained more likely to die than non-Māori even after adjusting for confounding and mediating variables.

Unstaged cancer in a population-based registry Prevalence, predictors and patient prognosis

PURPOSE Information on cancer stage at diagnosis is critical for population studies investigating cancer care and outcomes. Few studies have examined the factors which impact (1) staging or (2) outcomes for patients who are registered as having unknown stage. This study investigated (1) the prevalence of unknown stage at diagnosis on the New Zealand Cancer Registry (NZCR); (2) explored factors which predict unknown stage; (3) described receipt of surgery and (4) survival outcomes for patients with unknown stage. METHODS Patients diagnosed with the most prevalent 18 cancers between 2006 and 2008 (N=41,489) were identified from the NZCR, with additional data obtained from mortality and hospitalisation databases. Logistic and Cox regression were used to investigate predictors of unknown stage and patient outcomes. RESULTS (1) Three distinct groups of cancers were found based on proportion of patients with unknown stage (low=up to 33% unknown stage; moderate=33-64%; high=65%+). (2) Increasing age was a significant predictor of unknown stage (adjusted odds ratios [ORs]: 1.18-1.24 per 5-year increase across groups). Patients with substantive comorbidity were more likely to have unknown stage but only for those cancers with a low (OR=2.65 [2.28-3.09]) or moderate (OR=1.17 [1.03-1.33]) proportion of patients with unknown stage. (3) Patients with unknown stage were significantly less likely to have received definitive surgery than those with local or regional disease across investigated cancers. (4) Patients with unknown stage had 28-day and 1-year survival which was intermediate between regional and distant disease. DISCUSSION We found that stage completeness differs widely by cancer site. In many cases, the proportion of unknown stage on a population-based register can be explained by patient, service and/or cancer related factors.

The Māori foot exhibits differences in plantar loading and midfoot morphology to the Caucasian foot.

The question being addressed in the current study was whether the diabetic Māori foot was more or less prone to ulceration than the diabetic New Zealand Caucasian (NZC) foot. Harris mat and pedobarographic analyses were employed to assess static and dynamic foot morphology and plantar loading in 40 Māori and NZC diabetic and non-diabetic participants. Significantly higher peak pressures were exhibited by the diabetic Māori participants compared to their NZC peers at the central forefoot. Significantly higher static and dynamic arch index values and significantly higher sub-arch angle values were exhibited by the non-diabetic Māori participants compared to their NZC peers. The latter findings suggest that healthy Māori may have a predisposition towards having a flatter foot than healthy NZC, which may have footwear design implications.

A Comparison of Midwife-Led and Medical-Led Models of Care and Their Relationship to Adverse Fetal and Neonatal Outcomes: A Retrospective Cohort Study in New Zealand.

Background Internationally, a typical model of maternity care is a medically led system with varying levels of midwifery input. New Zealand has a midwife-led model of care, and there are movements in other countries to adopt such a system. There is a paucity of systemic evaluation that formally investigates safety-related outcomes in relationship to midwife-led care within an entire maternity service. The main objective of this study was to compare major adverse perinatal outcomes between midwife-led and medical-led maternity care in New Zealand. Methods and Findings This was a population-based retrospective cohort study. Participants were mother/baby pairs for all 244,047 singleton, term deliveries occurring between 1 January 2008 and 31 December 2012 in New Zealand in which no major fetal, neonatal, chromosomal or metabolic abnormality was identified and the mother was first registered with a midwife, obstetrician, or general practitioner as lead maternity carer. Main outcome measures were low Apgar score at five min, intrauterine hypoxia, birth-related asphyxia, neonatal encephalopathy, small for gestational age (as a negative control), and mortality outcomes (perinatal related mortality, stillbirth, and neonatal mortality). Logistic regression models were fitted, with crude and adjusted odds ratios (ORs) generated for each outcome for midwife-led versus medical-led care (based on lead maternity carer at first registration) with 95% confidence intervals. Fully adjusted models included age, ethnicity, deprivation, trimester of registration, parity, smoking, body mass index (BMI), and pre-existing diabetes and/or hypertension in the model. Of the 244,047 pregnancies included in the study, 223,385 (91.5%) were first registered with a midwife lead maternity carer, and 20,662 (8.5%) with a medical lead maternity carer. Adjusted ORs showed that medical-led births were associated with lower odds of an Apgar score of less than seven at 5 min (OR 0.52; 95% confidence interval 0.43–0.64), intrauterine hypoxia (OR 0.79; 0.62–1.02), birth-related asphyxia (OR 0.45; 0.32–0.62), and neonatal encephalopathy (OR 0.61; 0.38–0.97). No association was found between lead carer at first registration and being small for gestational age (SGA), which was included as a negative control (OR 1.00; 0.95–1.05). It was not possible to definitively determine whether one model of care was associated with fewer infant deaths, with ORs for the medical-led model compared with the midwife-led model being 0.80 (0.54–1.19) for perinatal related mortality, 0.86 (0.55–1.34) for stillbirth, and 0.62 (0.25–1.53) for neonatal mortality. Major limitations were related to the use of routine data in which some variables lacked detail; for example, we were unable to differentiate the midwife-led group into those who had received medical input during pregnancy and those who had not. Conclusions There is an unexplained excess of adverse events in midwife-led deliveries in New Zealand where midwives practice autonomously. The findings are of concern and demonstrate a need for further research that specifically investigates the reasons for the apparent excess of adverse outcomes in mothers with midwife-led care. These findings should be interpreted in the context of New Zealand’s internationally comparable birth outcomes and in the context of research that supports the many benefits of midwife-led care, such as greater patient satisfaction and lower intervention rates.

Test-retest reliability of dynamic plantar loading and foot geometry measures in diabetics with peripheral neuropathy

Pedobarography is commonly employed in patients with diabetic peripheral neuropathy (DPN). However there is no evidence regarding test-retest reliability of this technique in this population, and therefore it was the purpose of the current study to address this clear gap. Dynamic plantar loading and foot geometry data were collected during barefoot gait with the EMED platform (Novel GmbH, Germany) from 10 patients with DPN over two sessions, separated by 28 days. Intra-class Correlation Coefficients (ICCs) and Coefficients of Variation (CoVs) were calculated to determine test-retest reliability. For dynamic plantar loading, reliability differed by outcome measure and foot region, with ICCs of >0.8 and CoVs of <15% observed in most cases. For dynamic foot geometry, ICCs of >0.88 and CoVs of <3% were observed for hallux angle, arch index and coefficient of spreading, while sub-arch angle was less reliable (ICC 0.76, CoV 23%). Overall, the current study observed high levels of test-retest reliability which were generally commensurate with that previously reported in healthy populations.

Risk factors for cryptorchidism

Undescended testis — known as cryptorchidism — is one of the most common congenital abnormalities observed in boys, and is one of the few known risk factors for testicular cancer. The key factors that contribute to the occurrence of cryptorchidism remain elusive. Testicular descent is thought to occur during two hormonally-controlled phases in fetal development — between 8–15 weeks (the first phase of decent) and 25–35 weeks gestation (the second phase of descent); the failure of a testis to descend permanently is probably caused by disruptions to one or both of these phases, but the causes and mechanisms of such disruptions are still unclear. A broad range of putative risk factors have been evaluated in relation to the development of cryptorchidism but their plausibility is still in question. Consistent evidence of an association with cryptorchidism exists for only a few factors, and in those cases in which evidence seems unequivocal the factor is likely to be a surrogate for the true causal exposure. The relative importance of each risk factor could vary considerably between mother–son pairs depending on an array of genetic, maternal, placental and fetal factors — all of which could vary between regions. Thus, the role of causative factors in aetiology of cryptorchidism requires further research.