Safety and efficacy of antithrombotic therapy according to stroke and bleeding risk in patients with atrial fibrillation and acute coronary syndrome or PCI: insights from AUGUSTUS

Background

The AUGUSTUS trial showed that patients with atrial fibrillation (AF) and acute coronary syndrome (ACS) and/or PCI treated with a P2Y12 inhibitor and apixaban resulted in less bleeding and comparable ischemic events compared with regimens that included a vitamin K antagonist (VKA), aspirin, or both. We assessed the effect of apixaban versus VKA and aspirin versus placebo according to patients' baseline risk of stroke and bleeding.

Methods

AUGUSTUS randomized 4614 patients in a two-by-two factorial design to open label apixaban or VKA and blinded aspirin or placebo. The primary endpoint was major or clinically relevant nonmajor (CRNM) bleeding over 6 months of follow-up. The effects were assessed stratified by baseline CHA2DS2-VASc and HAS-BLED score using Cox proportional hazards models.

Results

4386 patients were included for this analysis. The median age was 71 (64–77) years, 29.4% were female, 81.7% had a CHA2DS2-VASc score≥3, and 66.8% a HAS-BLED score≥3. As shown in the table, rates of bleeding were lower with apixaban (vs VKA) irrespective of baseline bleeding risk (p-value interaction: 0.23). Aspirin (vs placebo) was associated with increased bleeding irrespective of baseline risk (p-value interaction: 0.88). Apixaban use was associated with a lower risk of death or hospitalization without a significant interaction with stroke risk (p-value of interaction=0.53). No differences were found for ischemic outcomes.

Conclusion

An antithrombotic regimen including a P2Y12 inhibitor and apixaban is associated with less bleeding and hospitalization compared to a regimen with VKA, aspirin, or both with results consistent across CHA2DS2-VASc, and HAS-BLED scores. Our findings support the use of apixaban and a P2Y12 inhibitor without aspirin during the first 6 months for most patients with AF and ACS and/or PCI, regardless of stroke and bleeding risk.

Funding Acknowledgement

Type of funding source: Private grant(s) and/or Sponsorship. Main funding source(s): The Augustus trial was sponsored by Bristol-Myers Squibb and Pfizer, Inc

P4752Apixaban 2.5 mg twice daily is effective and safe for patients with atrial fibrillation and combinations of advanced age, low body weight, and elevated creatinine: insights from ARISTOTLE

Background

In ARISTOTLE, patients with atrial fibrillation and ≥2 dose-reduction criteria [age ≥80 years, weight ≤60 kg, and creatinine ≥1.5 mg/dL (133 μmol/L)] were randomized to apixaban 2.5 mg twice daily (b.i.d) or warfarin.

Purpose

To determine whether the apixaban dose adjustment in ARISTOTLE resulted in similar efficacy and safety compared to warfarin.

Methods

The effects of apixaban 2.5 mg b.i.d versus warfarin on stroke or systemic embolism, major bleeding and death in ARISTOTLE patients with ≥2 dose-reduction criteria were compared with the effects of apixaban 5 mg b.i.d in patients with 0 or 1 dose-reduction criterion.

Results

Of 751 (4.1%) patients with ≥2 dose-reduction criteria, 386 were assigned to apixaban 2.5 mg b.i.d and 365 to warfarin. Compared to patients with 0 or 1 dose reduction criteria (n=17,322), these patients had a higher risks of stroke/systemic embolism (HR =1.78; 95% CI [1.24–2.57]), major bleeding (HR =1.73; 95% CI [1.28–2.32]) and death (HR=3.21; 95% CI [2.69–3.83]), irrespective of whether they were assigned to apixaban or warfarin. The benefits of apixaban 2.5 mg b.i.d compared with warfarin on stroke or systemic embolism, major bleeding, and death in patients with ≥2 dose-reduction criteria were consistent with that of apixaban 5 mg b.i.d in patients with either 0 or 1 dose-reduction criteria (Figure).

Conclusions

While they are at higher overall risk, patients with appropriate dose reduction criteria have consistent benefits with apixaban 2.5 mg b.i.d. over warfarin. Additional analyses investigating the relationship between apixaban dose and both apixaban plasma concentrations and levels of thrombosis biomarkers are underway.

Acknowledgement/Funding

Bristol-Myers Squibb and Pfizer, Inc.

Factors predictive of serious infections over time in systemic lupus erythematosus patients: data from a multi-ethnic, multi-national, Latin American lupus cohort

Aim

The aim of this study was to identify factors predictive of serious infections over time in patients with systemic lupus erythematosus (SLE).

Methods

A multi-ethnic, multi-national Latin American SLE cohort was studied. Serious infection was defined as one that required hospitalization, occurred during a hospitalization or led to death. Potential predictors included were sociodemographic factors, clinical manifestations (per organ involved, lymphopenia and leukopenia, independently) and previous infections at baseline. Disease activity (SLEDAI), damage (SLICC/ACR Damage Index), non-serious infections, glucocorticoids, antimalarials (users and non-users), and immunosuppressive drugs use; the last six variables were examined as time-dependent covariates. Cox regression models were used to evaluate the predictors of serious infections using a backward elimination procedure. Univariable and multivariable analyses were performed.

Results

Of the 1243 patients included, 1116 (89.8%) were female. The median (interquartile range) age at diagnosis and follow-up time were 27 (20–37) years and 47.8 (17.9–68.6) months, respectively. The incidence rate of serious infections was 3.8 cases per 100 person-years. Antimalarial use (hazard ratio: 0.69; 95% confidence interval (CI): 0.48–0.99; p = 0.0440) was protective, while doses of prednisone >15 and ≤60 mg/day (hazard ratio: 4.18; 95 %CI: 1.69–10.31; p = 0.0019) and >60 mg/day (hazard ratio: 4.71; 95% CI: 1.35–16.49; p = 0.0153), use of methylprednisolone pulses (hazard ratio: 1.53; 95% CI: 1.10–2.13; p = 0.0124), increase in disease activity (hazard ratio: 1.03; 95% CI: 1.01–1.04; p = 0.0016) and damage accrual (hazard ratio: 1.22; 95% CI: 1.11–1.34; p < 0.0001) were predictive factors of serious infections.

Conclusions

Over time, prednisone doses higher than 15 mg/day, use of methylprednisolone pulses, increase in disease activity and damage accrual were predictive of infections, whereas antimalarial use was protective against them in SLE patients.

Predictive factors of flares in systemic lupus erythematosus patients: data from a multiethnic Latin American cohort

Purpose The purpose of this paper is to determine the factors predictive of flares in systemic lupus erythematosus (SLE) patients. Methods A case-control study nested within the Grupo Latino Americano De Estudio de Lupus (GLADEL) cohort was conducted. Flare was defined as an increase ≥4 points in the SLEDAI. Cases were defined as patients with at least one flare. Controls were selected by matching cases by length of follow-up. Demographic and clinical manifestations were systematically recorded by a common protocol. Glucocorticoid use was recorded as average daily dose of prednisone and antimalarial use as percentage of time on antimalarial and categorized as never (0%), rarely (>0-25%), occasionally (>25%-50%), commonly (˃50%-75%) and frequently (˃75%). Immunosuppressive drugs were recorded as used or not used. The association between demographic, clinical manifestations, therapy and flares was examined using univariable and multivariable conditional logistic regression models. Results A total of 465 cases and controls were included. Mean age at diagnosis among cases and controls was 27.5 vs 29.9 years, p = 0.003; gender and ethnic distributions were comparable among both groups and so was the baseline SLEDAI. Independent factors protective of flares identified by multivariable analysis were older age at diagnosis (OR = 0.929 per every five years, 95% CI 0.869-0.975; p = 0.004) and antimalarial use (frequently vs never, OR = 0.722, 95% CI 0.522-0.998; p = 0.049) whereas azathioprine use (OR = 1.820, 95% CI 1.309-2.531; p < 0.001) and SLEDAI post-baseline were predictive of them (OR = 1.034, 95% CI 1.005-1.064; p = 0.022). Conclusions In this large, longitudinal Latin American cohort, older age at diagnosis and more frequent antimalarial use were protective whereas azathioprine use and higher disease activity were predictive of flares.

Pleuropulmonary involvement in patients with systemic lupus erythematosus from a Latin American inception cohort (GLADEL)

Objectives

The objectives of this study were to examine the demographic and clinical features associated with the occurrence of pleuropulmonary manifestations, the predictive factors of their occurrence and their impact on mortality in systemic lupus erythematosus (SLE) patients.

Materials and methods

The association of pleuropulmonary manifestations with demographic and clinical features, the predictive factors of their occurrence and their impact on mortality were examined in GLADEL patients by appropriate univariable and multivariable analyses.

Results

At least one pleuropulmonary manifestation occurred in 421 of the 1480 SLE patients (28.4%), pleurisy being the most frequent (24.0%). Age at SLE onset ≥30 years (OR 1.42; 95% CI 1.10–1.83), the presence of lower respiratory tract infection (OR 3.19; 95% CI 2.05–4.96), non-ischemic heart disease (OR 3.17; 95% CI 2.41–4.18), ischemic heart disease (OR 3.39; 95% CI 2.08–5.54), systemic (OR 2.00; 95% CI 1.37–2.91), ocular (OR 1.58; 95% CI 1.16–2.14) and renal manifestations (OR 1.44; 95% CI 1.09–1.83) were associated with pleuropulmonary manifestations, whereas cutaneous manifestations were negatively associated (OR 0.47; 95% CI 0.29–0.76). Non-ischemic heart disease (HR 2.24; 95% CI 1.63–3.09), SDI scores ≥1 (OR 1.54; 95% CI 1.10–2.17) and anti-La antibody positivity (OR 2.51; 95% CI 1.39–4.57) independently predicted their subsequent occurrence. Cutaneous manifestations were protective of the subsequent occurrence of pleuropulmonary manifestations (HR 0.62; 95% CI 0.43–0.90). Pleuropulmonary manifestations independently contributed a decreased survival (HR: 2.79 95% CI 1.80–4.31).

Conclusion

Pleuropulmonary manifestations are frequent in SLE, particularly pleuritis. Older age, respiratory tract infection, cardiac, systemic and renal involvement were associated with them, whereas cutaneous manifestations were negatively associated. Cardiac compromise, SDI scores ≥1 and anti-La positivity at disease onset were predictive of their subsequent occurrence, whereas cutaneous manifestations were protective. They independently contributed to a decreased survival in these patients.

Early discoid lupus erythematosus protects against renal disease in patients with systemic lupus erythematosus: longitudinal data from a large Latin American cohort

Objectives

The objective of this study was to examine whether early discoid lupus erythematosus (DLE) would be a protective factor for further lupus nephritis in patients with systemic lupus erythematosus (SLE).

Methods

We studied SLE patients from GLADEL, an inception longitudinal cohort from nine Latin American countries. The main predictor was DLE onset, which was defined as physician-documented DLE at SLE diagnosis. The outcome was time from the diagnosis of SLE to new lupus nephritis. Univariate and multivariate survival analyses were conducted to examine the association of DLE onset with time to lupus nephritis.

Results

Among 845 GLADEL patients, 204 (24.1%) developed lupus nephritis after SLE diagnosis. Of them, 10 (4.9%) had DLE onset, compared to 83 (12.9%) in the group of 641 patients that remained free of lupus nephritis (hazard ratio 0.39; P = 0.0033). The cumulative proportion of lupus nephritis at 1 and 5 years since SLE diagnosis was 6% and 14%, respectively, in the DLE onset group, compared to 14% and 29% in those without DLE ( P = 0.0023). DLE onset was independently associated with a lower risk of lupus nephritis, after controlling for sociodemographic factors and disease severity at diagnosis (hazard ratio 0.38; 95% confidence interval 0.20–0.71).

Conclusions

Our data indicate that DLE onset reduces the risk of further lupus nephritis in patients with SLE, independently of other factors such as age, ethnicity, disease activity, and organ damage. These findings have relevant prognosis implications for SLE patients and their clinicians. Further studies are warranted to unravel the biological and environmental pathways associated with the protective role of DLE against renal disease in patients with SLE.

Lupus in Latin-American patients: lessons from the GLADEL cohort

The need for comprehensive published epidemiologic and clinical data from Latin American systemic lupus erythematosus (SLE) patients motivated the late Dr Alarcón-Segovia and other Latin American professionals taking care of these patients to spearhead the creation of the G: rupo L: atino A: mericano D: e E: studio del L: upus (GLADEL) cohort in 1997. This inception cohort recruited a total of 1480 multiethnic (Mestizo, African-Latin American (ALA), Caucasian and other) SLE patients diagnosed within two years from the time of enrollment from 34 Latin American centers with expertise in the diagnosis and management of this disease. In addition to the initial 2004 description of the cohort, GLADEL has contributed to improving our knowledge about the course and outcome of lupus in patients from this part of the Americas. The major findings from this cohort are highlighted in this review. They have had important clinical implications for the adequate care of SLE patients both in Latin America and worldwide where these patients may have emigrated.

Late-onset systemic lupus erythematosus in Latin Americans: a distinct subgroup?

OBJECTIVE

To examine the characteristics of patients who developed late onset systemic lupus erythematosus (SLE) in the GLADEL (Grupo Latino Americano de Estudio del Lupus) cohort of patients with SLE.

METHODS

Patients with SLE of less than two years of disease duration, seen at 34 centers of nine Latin American countries, were included. Late-onset was defined as >50 years of age at time of first SLE-related symptom. Clinical and laboratory manifestations, activity index (SLEDAI), and damage index (SLICC/ACR- DI) were ascertained at time of entry and during the course (cumulative incidence). Features were compared between the two patient groups (<50 and ≥50) using descriptive statistics and hypothesis tests. Logistic regression was performed to examine the association of late-onset lupus, adjusting for other variables.

RESULTS

Of the 1480 patients included, 102 patients (6.9 %) had late-onset SLE, 87% of which were female. Patients with late-onset SLE had a shorter follow-up (3.6 vs. 4.4 years, p < 0.002) and a longer time to diagnosis (10.1 vs. 5.8 months, p < 0.001) compared to the younger onset group. Malar rash, photosensitivity, and renal involvement were less prevalent while interstitial lung disease, pleural effusions, and sicca symptoms were more frequent in the older age group (p > 0.05). In multivariable analysis, late onset was independently associated with higher odds of ocular (OR = 3.66, 95% CI = 2.15-6.23), pulmonary (OR = 2.04, 95% CI = 1.01-4.11), and cardiovascular (OR = 1.76, 95% CI = 1.04-2.98) involvement and lower odds of cutaneous involvement (OR = 0.41, 95% CI = 0.21-0.80), number of cumulative SLE criteria (OR = 0.79, 95% CI = 0.64-0.97), use of cyclophosphamide (OR = 0.47, 95% CI = 0.24-0.95), and anti-RNP antibodies (OR = 0.43, 95% CI = 0.20-0.91). A Cox regression model revealed a higher risk of dying in older onset than the younger-onset SLE (OR = 2.61, 95% CI = 1.2-5.6).

CONCLUSION

Late-onset SLE in Latin Americans had a distinct disease expression compared to the younger-onset group. The disease seems to be mild with lower cumulative SLE criteria, reduced renal/mucocutaneous involvements, and less use of cyclophosphamide. Nevertheless, these patients have a higher risk of death and of ocular, pulmonary, and cardiovascular involvements.

The American College of Rheumatology and the Systemic Lupus International Collaborating Clinics Classification criteria for systemic lupus erythematosus in two multiethnic cohorts: a commentary

The authors offer some comments on the advantages and possible drawbacks of using the SLICC criteria in longitudinal observational studies and clinical trials after applying and comparing them to the ACR criteria in two multinational, multiethnic lupus cohorts.

Mestizos with systemic lupus erythematosus develop renal disease early while antimalarials retard its appearance: data from a Latin American cohort

OBJECTIVES

The objective of this paper is to assess the predictors of time-to-lupus renal disease in Latin American patients.

METHODS

Systemic lupus erythematosus (SLE) patients (n = 1480) from Grupo Latino Americano De Estudio de Lupus (GLADEL's) longitudinal inception cohort were studied. Endpoint was ACR renal criterion development after SLE diagnosis (prevalent cases excluded). Renal disease predictors were examined by univariable and multivariable Cox proportional hazards regression analyses. Antimalarials were considered time dependent in alternative analyses.

RESULTS

Of the entire cohort, 265 patients (17.9%) developed renal disease after entering the cohort. Of them, 88 (33.2%) developed persistent proteinuria, 44 (16.6%) cellular casts and 133 (50.2%) both; 233 patients (87.9%) were women; mean (± SD) age at diagnosis was 28.0 (11.9) years; 12.2% were African-Latin Americans, 42.5% Mestizos, and 45.3% Caucasians (p = 0.0016). Mestizo ethnicity (HR 1.61, 95% CI 1.19-2.17), hypertension (HR 3.99, 95% CI 3.02-5.26) and SLEDAI at diagnosis (HR 1.04, 95% CI 1.01-1.06) were associated with a shorter time-to-renal disease occurrence; antimalarial use (HR 0.57, 95% CI 0.43-0.77), older age at onset (HR 0.90, 95% CI 0.85-0.95, for every five years) and photosensitivity (HR 0.74, 95% CI 0.56-0.98) were associated with a longer time. Alternative model results were consistent with the antimalarial protective effect (HR 0.70, 95% CI 0.50-0.99).

CONCLUSIONS

Our data strongly support the fact that Mestizo patients are at increased risk of developing renal disease early while antimalarials seem to delay the appearance of this SLE manifestation. These data have important implications for the treatment of these patients regardless of their geographic location.

The impact of rural residency on the expression and outcome of systemic lupus erythematosus: data from a multiethnic Latin American cohort

OBJECTIVE

The objective of this paper is to examine the role of place of residency in the expression and outcomes of systemic lupus erythematosus (SLE) in a multi-ethnic Latin American cohort.

PATIENTS AND METHODS

SLE patients (< two years of diagnosis) from 34 centers constitute this cohort. Residency was dichotomized into rural and urban, cut-off: 10,000 inhabitants. Socio-demographic, clinical/laboratory and mortality rates were compared between them using descriptive tests. The influence of place of residency on disease activity at diagnosis and renal disease was examined by multivariable regression analyses.

RESULTS

Of 1426 patients, 122 (8.6%) were rural residents. Their median ages (onset, diagnosis) were 23.5 and 25.5 years; 85 (69.7%) patients were Mestizos, 28 (22.9%) Caucasians and 9 (7.4%) were African-Latin Americans. Rural residents were more frequently younger at diagnosis, Mestizo and uninsured; they also had fewer years of education and lower socioeconomic status, exhibited hypertension and renal disease more frequently, and had higher levels of disease activity at diagnosis; they used methotrexate, cyclophosphamide pulses and hemodialysis more frequently than urban patients. Disease activity over time, renal damage, overall damage and the proportion of deceased patients were comparable in rural and urban patients. In multivariable analyses, rural residency was associated with high levels of disease activity at diagnosis (OR 1.65, 95% CI 1.06-2.57) and renal disease occurrence (OR 1.77, 95% CI 1.00-3.11).

CONCLUSIONS

Rural residency associates with Mestizo ethnicity, lower socioeconomic status and renal disease occurrence. It also plays a role in disease activity at diagnosis and kidney involvement but not on the other end-points examined.

Two mifepristone doses and two intervals of misoprostol administration for termination of early pregnancy: a randomised factorial controlled equivalence trial

OBJECTIVE

To compare the efficacy of 100 mg and 200 mg of mifepristone and 24- and 48-hour intervals to administration of 800 microg vaginal misoprostol for termination of early pregnancy.

DESIGN

Placebo-controlled, randomized, equivalence trial, stratified by centre.

SETTING

13 departments of obstetrics and gynecology in nine countries.

POPULATION

2,181 women with 63 days or less gestation requesting medical abortion.

METHODS

Two-sided 95% CI for the risk differences of failure to complete abortion were calculated and compared with 5% equivalence margin between two doses of mifepristone and two intervals to misoprostol administration. Proportions of women with adverse effects were compared between the regimens using standard testes for proportions.

OUTCOME MEASURES

Rates of complete abortion without surgical intervention and adverse effects associated with the regimens.

RESULTS

Efficacy outcome was analysed for 2,126 women (97.5%) excluding 55 lost to follow up. Both mifepristone doses were found to be similar in efficacy. The rate of complete abortion was 92.0% for women assigned 100 mg of mifepristone and 93.2% for women assigned 200 mg of mifepristone (difference 1.2%, 95% CI: -1.0 to 3.5). Equivalence was also evident for the two intervals of administration: the rate of complete abortion was 93.5% for 24-hour interval and 91.7% for the 48-hour interval (difference -1.8%, 95% CI: -4.0 to 0.5). Interaction between doses and interval to misoprostol administration was not significant (P = 0.92). Adverse effects related to treatments did not differ between the groups.

CONCLUSIONS

Both the 100 and 200 mg doses of mifepristone and the 24- and 48-hour intervals have a similar efficacy to achieve complete abortion in early pregnancy when mifepristone is followed by 800 micrograms of vaginally administered misoprostol.

Childhood systemic lupus erythematosus in Latin America. The GLADEL experience in 230 children

To evaluate disease characteristics of childhood onset SLE in Latin America and to compare this information with an adult population in the same cohort of GLADEL. A protocol was designed as a multicenter, multinational, inception cohort of lupus patients to evaluate demographic, clinical, laboratory and serological variables, as well as classification criteria, disease activity, organ damage and mortality. Descriptive statistics, chi square, Fisher's exact test, Student's t test and multiple logistic regression were used to compare childhood and adult onset SLE. 230 patients were <18 years and 884 were adult SLE patients. Malar rash, fever, oral ulcers, thrombocytopenia and hemolytic anemia and some neurologic manifestations were more prevalent in children (p<0.05). On the other hand, myalgias, Sjögren's syndrome and cranial nerve involvement were more frequently seen in adults (p<0.05). Afro-Latin-American children had a higher prevalence of fever, thrombocytopenia and hemolytic anemia. White and mestizo children had a higher prevalence of malar rash. Mestizo children had a higher prevalence of cerebrovascular disease and cranial nerve involvement. Children met SLE ACR criteria earlier with higher mean values than adults (p: 0.001). They also had higher disease activity scores (p: 0.01), whereas adults had greater disease damage (p: 0.02). In Latin America, childhood onset SLE seems to be a more severe disease than adults. Some differences can be detected among ethnic groups.

Improved outcome of Trypanosoma cruzi infection in rats following treatment in early life with suspensions of heat-killed environmental Actinomycetales

The well-established model of Chagas' disease in "l" rats was used to evaluate the effects of three injections of heat-killed Gordonia bronchialis, Rhodococcus coprophilus or saline on Trypanosoma cruzi parasitaemia and acute and chronic myocarditis, sequelae of the infection. Two vaccinating injections were given prior to challenge with T. cruzi, and the third, immunotherapeutic, injection was given 7 days after challenge. Treatment with either actinomycete significantly reduced acute parasitaemia (p<0.04), modified cellular infiltration during acute myocarditis and limited chronic myocarditis (p<0.03) in comparison with the saline-treated control animals. Immunological investigations showed that both bacterial preparations achieved their results through different mechanisms. The relevance of our findings to human Chagas' disease is discussed.

Male systemic lupus erythematosus in a Latin-American inception cohort of 1214 patients

The objective of the study was to evaluate the influence of the male gender in the clinical presentation and outcome of systemic lupus erythematosus in a prospective inception cohort of Latin-American patients. Of the 1214 SLE patients included in the GLADEL cohort, 123 were male. Demographic characteristics as well as clinical manifestations, laboratory profile, activity and damage scores were evaluated at onset and during the course of the disease and compared with female patients. The median age at onset of the male patients was 27 and that at diagnosis 29.2 years. Delay to diagnosis was shorter in males (134 versus 185 days, P = 0.01). At onset, men more frequently showed fever (42.3 versus 27.0%, P = 0.001) and weight loss (23.6 versus 11.8%, P = 0.001). During disease course the incident of symptoms was: fever, 67.8 versus 55.6%, P = 0.012; weight loss, 47.2 versus 24.3%, P = 0.001; arterial hypertension, 37.4 versus 25.8%, P = 0.007; renal disease (persistent proteinuria and/or cellular casts), 58.5 versus 44.6%, P = 0.004); and hemolytic anemia, 19.5 versus 10.9%, P = 0.008. The laboratory results showed that: men more frequently had IgG anticardiolipin antibodies (68.2 versus 49%, P = 0.02) and low C3 (61.3 versus 48.1%, P = 0.03); 5/123 men died (4%) compared with 29/1091 women (2.7%). In conclusion, 10% of GLADEL's cohort patients were male. They showed a distinctive profile with shorter delay to diagnosis, higher incidence of fever, weight loss, arterial hypertension, renal disease, hemolytic anemia, IgG anticardiolipin antibodies and low C3. Although not statistically significant, mortality was higher in men.

Cluster analysis with constraints: its use with breast cancer mortality rates in Argentina

One approach to analyse geographic variations of a disease within a country is through mortality rates in administrative areas. In some geographical areas the rates can be unstable due to their low population. Thus, the statistical analysis of the rate could be not significant due to low population, not because of the real value. An alternative approach to this problem is to set a minimum level of population that enables valid statistical comparisons with the national rate to be made. It is decided to apply an algorithm that groups neighbouring geographical units that reach the minimum population. In the resulting regions, mortality rates are calculated, and the geographic patterns are analysed through the Moran's I coefficient of spatial clustering. This paper presents an application of this approach to mortality rates from breast cancer by Argentine departments, political administrative units into which a province is divided. Applying this procedure, 217 regions were obtained. In two of the regions the rates were significantly higher than the national rate, while in 40 regions they were significantly lower. Significant spatial grouping, reflected by a Moran I coefficient of O-47, was observed.