Monitoring chronic diseases in Canada: the Chronic Disease Indicator Framework.

INTRODUCTION: The Public Health Agency of Canada developed the Chronic Disease Indicator Framework (the Framework) with the goal of systematizing and enhancing chronic disease surveillance in Canada by providing the basis for consistent and reliable information on chronic diseases and their determinants. METHODS: Available national and international health indicators, frameworks and national health databases were reviewed to identify potential indicators. To make sure that a comprehensive and balanced set of indicators relevant to chronic disease prevention was included, a conceptual model with "core domains" for grouping eligible indicators was developed. Specific selection criteria were applied to identify key measures. Extensive consultations with a broad range of government partners, non-governmental organizations and public health practitioners were conducted to reach consensus and refine and validate the Framework. RESULTS: The Framework contains 41 indicators organized in a model comprised of 6 core domains: social and environmental determinants, early life / childhood risk and protective factors, behavioural risk and protective factors, risk conditions, disease prevention practices, and health outcomes/status. Also planned is an annual release of updated data on the proposed set of indicators, including national estimates, breakdowns by demographic and socioeconomic variables, and time trends. CONCLUSIONS: Understanding the evidence related to chronic diseases and theirdeterminants is key to interpreting trends and crucial to the development of public health interventions. The Framework and its related products have the potential of becoming an indispensable tool for evidence-informed decision making in Canada.

TITRE: Surveillance des maladies chroniques au Canada : Cadre conceptuel d'indicateurs des maladies chroniques. INTRODUCTION: L'Agence de la santé publique du Canada a conçu le Cadre conceptuel d'indicateurs des maladies chroniques (le Cadre) dans le but de systématiser et d'améliorer la surveillance des maladies chroniques au Canada en instaurant les fondements d'une information uniforme et fiable sur les maladies chroniques et leurs déterminants. MÉTHODOLOGIE: Des indicateurs de santé nationaux et internationaux, des cadres conceptuels ainsi que des bases de données sur la santé nationale ont été examinés pour identifier les indicateurs potentiels. Pour s'assurer d'obtenir un ensemble complet et équilibré d'indicateurs pertinents en matière de prévention des maladies chroniques, nous avons élaboré un modèle conceptuel comprenant des « champs de référence ¼ pour le regroupement des indicateurs. Plusieurs critères de sélection ont été appliqués pour le choix des mesures clés. Des consultations approfondies avec un large éventail de partenaires du gouvernement, d'organismes non gouvernementaux et de professionnels de la santé publique ont été réalisées pour en arriver à un consensus et pour perfectionner et valider le Cadre. RÉSULTATS: Le Cadre comprend 41 indicateurs structurés autour de 6 champs de référence : les déterminants sociaux et environnementaux, les facteurs de risque et de protection en bas âge, les facteurs de risque et de protection comportementaux, les conditions à risque, les pratiques de prévention des maladies, l'état de santé global et les impacts sur la santé. Nous avons aussi prévu une mise à jour annuelle des données touchant l'ensemble des indicateurs proposés, que ce soit les estimations nationales, les ventilations par variables démographiques et socioéconomiques ou les tendances temporelles. CONCLUSION: Comprendre les données probantes liées aux maladies chroniques et leurs déterminants est nécessaire pour interpréter les tendances et crucial pour élaborer des interventions efficaces en matière de santé publique. Le Cadre et ses produits connexes sont susceptibles de devenir un outil indispensable d'aide à la décision axée sur des données probantes au Canada.

Predictors of post-thrombotic syndrome in a population with a first deep vein thrombosis and no primary venous insufficiency.

BACKGROUND: Post-thrombotic syndrome (PTS) is the most frequent complication of deep vein thrombosis (DVT). Its diagnosis is based on clinical characteristics. However, symptoms and signs of PTS are non-specific, and could result from concomitant primary venous insufficiency (PVI) rather than DVT. This could bias evaluation of PTS. METHODS: Using data from the REVERSE multicenter study, we assessed risk factors for PTS in patients with a first unprovoked unilateral proximal DVT 5-7 months earlier who were free of clinically significant PVI (defined as absence of moderate or severe venous ectasia in the contralateral leg). RESULTS: Among the 328 patients considered, the prevalence of PTS was 27.1%. Obesity (odds ratio [OR] 2.6 [95% confidence interval (CI) 1.5-4.7]), mild contralateral venous ectasia (OR 2.2 [95% CI 1.1-4.3]), poor International Normalized Ratio (INR) control (OR per additional 1% of time with INR < 2 during anticoagulant treatment of 1.018 [95% CI 1.003-1.034]) and the presence of residual venous obstruction on ultrasound (OR 2.1 [95% CI 1.1-3.7]) significantly increased the risk for PTS in multivariable analyses. When we restricted our analysis to patients without any signs, even mild, of contralateral venous insufficiency (n = 244), the prevalence of PTS decreased slightly to 24.6%. Only obesity remained an independent predictor of PTS (OR 2.6 [95% CI 1.3-5.0]). Poor INR control and residual venous obstruction also increased the risk, but the results were no longer statistically significant (OR 1.017 [95% CI 0.999-1.035] and OR 1.7 [95% CI 0.9-3.3], respectively). CONCLUSIONS: After a first unprovoked proximal DVT, obese patients and patients with even mild PVI constitute a group at increased risk of developing PTS for whom particular attention should be paid with respect to PTS prevention. Careful monitoring of anticoagulant treatment may prevent PTS.

Risk of post-thrombotic syndrome after subtherapeutic warfarin anticoagulation for a first unprovoked deep vein thrombosis: results from the REVERSE study.

BACKGROUND: Risk factors for post-thrombotic syndrome (PTS) remain poorly understood. OBJECTIVES: In this multinational multicenter study, we evaluated whether subtherapeutic warfarin anticoagulation was associated with the development of PTS. METHODS: Patients with a first unprovoked deep venous thrombosis (DVT) received standard anticoagulation for 5-7 months and were then assessed for PTS. The time in the therapeutic range was calculated from the international normalized ratio (INR) data. An INR below 2, more than 20% of the time, was considered as subtherapeutic anticoagulation. RESULTS: Of the 349 patients enrolled, 97 (28%) developed PTS. The overall frequency of PTS in patients with subtherapeutic anticoagulation was 33.5%, compared with 21.6% in those with an INR below two for ≤ 20% of the time (P = 0.01). During the first 3 months of therapy, the odds ratio (OR) for developing PTS if a patient had subtherapeutic anticoagulation was 1.78 (95% confidence interval [CI] 1.10-2.87). After adjusting for confounding variables, the OR was 1.84 (95% CI 1.13-3.01). Corresponding ORs for the full period of anticoagulation were 1.83 (95% CI 1.14-3.00) [crude] and 1.88 (95% CI 1.15-3.07) [adjusted]. CONCLUSION: Subtherapeutic warfarin anticoagulation after a first unprovoked DVT was significantly associated with the development of PTS.

Comparison of the Villalta post-thrombotic syndrome score in the ipsilateral vs. contralateral leg after a first unprovoked deep vein thrombosis.

BACKGROUND: Post-thrombotic syndrome (PTS) is the most frequent complication of a deep vein thrombosis (DVT). International guidelines recommend assessing PTS with the Villalta scale, a clinical measure that incorporates venous symptoms and signs in the leg ipsilateral to a DVT. However, these signs and symptoms are not specific for PTS and their prevalence and relevance in the contralateral leg have not previously been studied. METHODS: Using data from the REVERSE prospective multicentre cohort study, we compared the Villalta total score and prevalence of venous signs and symptoms in the ipsilateral vs. contralateral leg in patients with a first, unilateral DVT 5 to 7 months previously. RESULTS: Among the 367 patients analyzed, the mean Villalta score was higher in the ipsilateral than in the contralateral leg (mean ± standard deviation [SD] 3.7 [3.4] vs. 1.9 [2.5], respectively; P<0.0001). Villalta scores in the ipsilateral and contralateral legs were strongly correlated (r=0.68; P<0.0001). Ipsilateral PTS (defined by a Villalta total score >4) was present in 31.6% (n=116) of patients. Among these, 39.7% (n=46) of patients had a Villalta score >4 in the contralateral leg, and the distribution of Villalta symptoms and signs components was similar between the legs. CONCLUSIONS: Villalta scores in the ipsilateral and contralateral legs are strongly correlated. Almost half of cases considered to be PTS might reflect pre-existing symptomatic chronic venous disease. Alternatively, patients with pre-existing chronic venous disease might be more prone to developing PTS after a DVT. Performing a bilateral assessment of Villalta scores at the acute phase of DVT could be of clinical interest from a diagnostic, prognostic and therapeutic point of view.

Residual vein obstruction as a predictor for recurrent thromboembolic events after a first unprovoked episode: data from the REVERSE cohort study.

OBJECTIVES: There is growing interest in using residual vein obstruction (RVO) to guide the duration of oral anticoagulant therapy (OAT) for unprovoked deep vein thrombosis (DVT). We sought to determine if RVO as determined by compression ultrasonography (CUS) after completion of 5-7 months of anticoagulation for unprovoked DVT is associated with an increased risk of recurrent venous thromboembolism (VTE). MATERIALS AND METHODS: This was a multicentre multinational prospective cohort study undertaken in tertiary care centers. Patients with a first 'unprovoked' major VTE were enrolled over a 4-year period and completed a mean 18-month follow-up in September 2006. All 452 patients with DVT had baseline CUS at inclusion to assess any RVO before stopping OAT at 5-7 months. During follow-up off OAT, all episodes of suspected recurrent VTE were independently adjudicated with reference to baseline imaging. RESULTS: Forty-five out of 231 patients with abnormal CUS (19.5%) had recurrent VTE during follow-up, as compared with 32 out of 220 patients with normal CUS (14.6%), and one patient had inadequate CUS. There was no significant association between an abnormal CUS at inclusion and the risk of recurrent VTE: hazard ratio 1.4 (95% confidence interval, 0.9-2.1), P=0.19. None of the different degrees of clot resolution on baseline CUS was statistically significantly associated with the risk of recurrent VTE. CONCLUSION: In our study, the presence of RVO at the time of OAT withdrawal was not associated with a statistically significant higher risk of recurrent VTE. RVO assessment may not be useful to guide duration of anticoagulation.

Serum lipoprotein (a) levels in patients with first unprovoked venous thromboembolism is not associated with subsequent risk of recurrent VTE.

INTRODUCTION: Case-control studies suggest that elevated lipoprotein (a) (Lp(a)) is a risk factor for first venous thromboembolism (VTE). Lp(a) has not been prospectively investigated as a possible risk factor for recurrent VTE in first unprovoked VTE patients. We sought to determine if serum Lp(a) levels in patients with unprovoked VTE who discontinue anticoagulants after 5 to 7 months of therapy predict VTE recurrence in a prospective cohort study. MATERIALS AND METHODS: Serum Lp(a) measurements were obtained from 510 first unprovoked VTE patients treated for 5 -7 months with anticoagulants in a 12 center study. Patients were subsequently followed for a mean of 16.9 months (SD+/-11.2) for symptomatic VTE recurrence which was independently adjudicated with reference to baseline imaging. RESULTS: There was no significant association between Lp(a) as a continuous variable and recurrent VTE nor in gender stratified subgroups. No statistically significant differences were observed in the median Lp(a) concentrations between patients who recurred and those who did not recur (median (interquartile range): 0.09 g/L (0.17) versus 0.06 g/L (0.11) respectively; p=0.15). The Lp(a) cut-off point of 0.3g/L was not significantly associated with recurrent VTE for the overall population nor in gender stratified subgroups. CONCLUSIONS: Elevated serum Lp(a) does not appear to be associated with recurrent VTE in patients with history of first unprovoked VTE and may not play a role in identifying patients with unprovoked VTE at high risk of recurrence. There was no optimal predictive threshold for the overall population or for sex sub-groups and Lp(a)>or=0.3 g/L was not a significant predictor of recurrent VTE.

Patients with a first symptomatic unprovoked deep vein thrombosis are at higher risk of recurrent venous thromboembolism than patients with a first unprovoked pulmonary embolism.

BACKGROUND: Previous studies are mixed as to whether patients with unprovoked pulmonary embolism (PE) have a higher rate of venous thromboembolism (VTE) recurrence after anticoagulation is discontinued than patients with unprovoked deep vein thrombosis (DVT). OBJECTIVES: To determine whether patients with unprovoked PE have a higher rate of VTE recurrence than patients with unprovoked DVT in a prospective multicenter cohort study. PATIENTS/METHODS: Six hundred and forty-six patients with a first episode of symptomatic unprovoked VTE were treated with heparin and subsequent oral anticoagulation for 5-7 months, and were followed every 6 months for recurrent VTE after their anticoagulant therapy was discontinued. RESULTS: Of 646 patients, 194 had isolated PE, 339 had isolated DVT, and 113 had both DVT and PE. After a mean of 18 months of follow-up, there were 91 recurrent VTE events (9.5% annualized risk of recurrent VTE in the total population). The crude recurrent VTE rate for the isolated PE, isolated DVT and DVT and PE groups were 7.7%, 16.5% and 17.7%, respectively. The relative risk of recurrent VTE for isolated DVT vs. isolated PE was 2.1 (95% confidence interval 1.2-3.7). CONCLUSIONS: This study has demonstrated that patients with a first episode of unprovoked isolated DVT are 2.1 times more likely to have a recurrent VTE episode than patients with a first episode of unprovoked isolated PE. These findings need to be considered when determining the optimal duration of anticoagulant therapy for patients with unprovoked VTE.

Risk stratification for recurrent venous thromboembolism in unprovoked venous thromboembolism patients.

Unprovoked venous thromboembolism (VTE) patients are at much higher risk of a recurrent VTE event than provoked VTE patients. Oral anticoagulation therapy (OAT) after a first unprovoked VTE has proved to effectively reduce the risk of recurrence during therapy however this benefit is lost after discontinuing OAT. A minimum of 6 to 12 months of OAT is recommended for first unprovoked VTE patients to prevent recurrence. However, there is evidence indicating that some patients are at ongoing high risk of recurrent VTE after discontinuation of therapy and that these patients may need indefinite anticoagulation to effectively prevent recurrences. Several risk factors for recurrent VTE have been identified that may be helpful to physicians when deciding whether OAT should be continued or discontinued in unprovoked VTE patients after initial therapy. The present article reviews risk factors for recurrent VTE including D-Dimer levels after discontinuation of OAT, elevated levels of Factor VIII, residual venous obstruction, post-thrombotic syndrome, male gender, and older age. Research is also underway to determine the predictive ability of these known VTE recurrence risk factors, combinations of these risk factors and their interrelationships as well as to actively search for additional potential predictors.