Progression of myopia in teenagers and adults: a nationwide longitudinal study of a prevalent cohort

BackgroundThe prevalence of myopia is increasing worldwide. The purpose of this study was to evaluate the progression of myopia in teenagers and adults in France.MethodsThis nationwide prospective study followed 630 487 myopic adults and teenagers (mean age 43.4 years±18.2, 59.8% of women) between January 2013 and January 2019. Myopia and high myopia were defined as a spherical equivalent less than or equal to –0.50 and –6.00 diopters (D), respectively. Demographic data were collected at first visit and refractive characteristics were collected at each visit. Analysis of short-term progression (first 12 to 26 months postbaseline) was modelled using analysis of variance (ANOVA). Progression of myopia was stratified according to age, gender and spherical equivalent at first visit.ResultsHigher proportions of progressors were observed in the youngest age groups: 14–15 (18.2 %) and 16–17 years old (13.9 %). In multivariate analysis, after adjustment for over age, spherical equivalent and gender, the mean short-term progression decreased from –0.36 D in the 14–15 years age group to –0.13 D in the 28–29 years age group. Young age and higher myopia at baseline together were strongly associated with the risk of developing high myopia, the 5-year cumulative risk being 76% for youngest teenager with higher myopia status at baseline.ConclusionIn this large cohort of myopic teenagers and adults, myopia progression was reported in 18.2% and 13.9% of the 14–15 and 16–17 age groups, respectively. The risk to develop high myopia was higher for younger individuals with higher myopia at baseline examination.

Abstract 17272: Frequency of Acute Vasodilator Response in Incident and Prevalent Patients With Pulmonary Arterial Hypertension (Group 1): Results From the Pulmonary Vascular Disease Omics (PVDOMICS) Study

Introduction: The prevalence of acute vasodilator response (AVR) to inhaled NO (defined as a reduction in mPAP ≥ 10 mmHg with an absolute value of mPAP ≤ 40 mmHg with increased/unchanged CO) is reported to be around 12% in incident patients with idiopathic PAH (IPAH). The prevalence of AVR, however, is reportedly lower in other disease-associated PAH in Group 1, such as connective tissue disease (CTD). Furthermore, the prevalence of AVR for combined inhaled NO and oxygen, and in patients on PAH therapy (prevalent cohort), is less known. Hypothesis: We hypothesized there would be differences in the prevalence of AVR in PAH subgroups in the large PVDOMICS cohort of incident and prevalent patients. Methods: Group 1 PAH patients enrolled in PVDOMICS underwent right heart catheterization for baseline measurements. AVR was then measured in response to 100% inhaled oxygen (O 2 ) and 100% O 2 plus NO at 40 ppm (O 2 +NO) for 5 min each before hemodynamic measurements. Details of the PVDOMICS methodology and core adjudication of hemodynamic measurements were reported previously. Rates of AVR to 100% O 2 and 100% O 2 +NO were compared between incident and prevalent patients in each PAH subgroup. Results: 351 patients, mostly female (73%), average age of 52.9 years, with mostly prevalent disease (87%) and an average of 4 years from PAH diagnosis, underwent AVR assessment. A positive AVR was found in 0.6% of patients in response to 100% oxygen and 6% of patients in response to 100%+NO for the overall cohort. AVR was similar in incident and prevalent IPAH patients (6 and 6.9%, respectively). It was, however, 0% and 6.9%, in incident vs. prevalent CTD-PAH patients, respectively. There were no responders to either challenge in any other PAH subgroup. Conclusions: The prevalence of AVR is relatively rare in IPAH and CTD-PAH (~ 6%) and absent in other subgroups. There was no response to 100% O2 alone, suggesting specificity of AVR to NO in PAH. AVR is more common than previously reported in CTD-PAH, but only in prevalent disease. Whether the latter is related to long-term PAH therapy affecting pulmonary vasomotor response and/or vascular remodeling in these patients would warrant further studies.

Parametric models for combined failure time data from an incident cohort study and a prevalent cohort study with follow-up

A classical problem in survival analysis is to estimate the failure time distribution from right-censored observations obtained from an incident cohort study. Frequently, however, failure time data comprise two independent samples, one from an incident cohort study and the other from a prevalent cohort study with follow-up, which is known to produce length-biased observed failure times. There are drawbacks to each of these two types of study when viewed separately. We address two main questions here: (i) Can our statistical inference be enhanced by combining data from an incident cohort study with data from a prevalent cohort study with follow-up? (ii) What statistical methods are appropriate for these combined data? The theory we develop to address these questions is based on a parametrically defined failure time distribution and is supported by simulations. We apply our methods to estimate the duration of hospital stays.

A64 HOSPITALIZATION IN INFLAMMATORY BOWEL DISEASE: A POPULATION-BASED COMPARISON OF DEFINITIONS

Background Most administrative studies of hospitalization in inflammatory bowel disease (IBD) use two definitions: IBD in any diagnostic position (IBD-ANY), and IBD as the most responsible diagnostic (IBD-MRD). There is a third less commonly used definition: total hospitalization; this definition captures all hospitalizations of prevalent IBD patients and therefore it can give a more realistic picture of the burden of IBD. Aims To compare differing definitions (total, IBD-ANY, and IBD-MRD) of hospitalizations. Methods A previously defined population-based IBD prevalent cohort for Alberta (n=30,698) was used to pull all hospital admissions from the Discharge Administrative Database (DAD; 2002–2015). Three hospitalization definitions were used: i. Total (all hospitalizations of prevalent cohort independent of presence of code for IBD); ii. IBD-ANY (code for IBD [K50.x; K51.x] contained in any diagnosis field); and, iii. IBD-MRD (most responsible diagnosis was IBD). Age- and sex- standardized rates (2015 Canadian population) were calculated using the prevalent population. Log-linear regression was performed to calculate Average Annual Percentage Change (AAPC) with associated 95% confidence intervals (CI) of each type of hospitalization. We assessed the top five most common most-responsible diagnosis codes for hospitalizations that were contained in the total hospitalizations but not an IBD-ANY hospitalization. Results From 2002 to 2015, 63.5% of IBD prevalent patients in AB had ≥1 hospitalization; 44.2% had ≥1 IBD-ANY hospitalization; 28.6% had ≥1 IBD-MRD hospitalization; and, 40.6% had a hospitalization that did not contain a code for IBD. All hospitalization rates decreased significantly over time. Of the top five most common most responsible diagnosis, contained in admissions that were not IBD-ANY, three were gastroenterological: i. K52.9 (non-infective gastroenteritis); ii. A09.9 (diarrhea and gastroenteritis of presumed infectious origin); and, iii. Z43.2 (attention to ileostomy). Conclusions Total hospitalizations is an important measure to report since accounting for all hospitalizations of IBD patients is necessary in order to allocate healthcare resources appropriately. To be able to ensure these patients receive the care they need we need to be able to accurately assess the true burden of IBD. Funding Agencies CIHR