Background: The characteristics of the target group and the design of an epidemiologic study, in particular the recruiting methods, can influence participation. People with vision impairment have unique characteristics because those invited are often elderly and totally or partially dependent on help to complete daily activities such as travelling to study sites. Therefore, participation of people with impaired vision in studies is less predictable than predicting participation for the general population. Methods: Participants were recruited in the context of a study of prevalence and costs of visual impairment in Portugal (PCVIP-study). Participants were recruited from 4 Portuguese public hospitals. Inclusion criteria were: acuity in the better eye from 0.5 decimal (0.30logMAR) or worse and/or visual field of less than 20 degrees. Recruitment involved sending invitation letters and follow-up phone calls. A multiple logistic regression model was used to assess determinants of participation. The J48 classifier, chi-square and Fisher's exact tests were applied to investigate the possible differences between subjects in our sample. Results: Individual cases were divided into 3 groups: immediate, late and non-participants. A participation rate of 20% was obtained (15% immediate, 5% late). Factors positively associated with participation included years of education, annual hospital attendance, and intermediate visual acuity. Females and greater distance to the hospital were inversely associated with participation. Conclusion: In our study, a letter followed by a phone call was efficient to recruit a significant number of participants from a larger group of people with impaired vision. However, the improvement in participation observed after the phone call might not be cost-effective. People with low levels of education and women were more difficult to recruit. These findings need to be considered to avoid studies whose results are biased by gender or socioeconomic inequalities of their participants. Young subjects and those at intermediate stages of vision impairment, or equivalent conditions, may need more persuasion than other profiles.

Epidemiological information is expected to be used to develop key aspects of eye care such as to control and minimise the impact of diseases, to allocate resources, to monitor public health actions, to determine the best treatment options and to forecast the consequence of diseases in populations. Epidemiological studies are expected to provide information about the prevalence and/or incidence of eye diseases or conditions. To determine prevalence is necessary to perform a cross-sectional screening of the population at risk to ascertain the number of cases.The aim of this review is to describe and evaluate capture-recapture methods (or models) to ascertaining the number of individuals with a disease (e.g. diabetic retinopathy) or condition (e.g. vision impairment) in the population.The review covers the fundamental aspects of capture-recapture methods that would enable non-experts in epidemiology to use it in ophthalmic studies. The review provides information about theoretical aspects of the method with examples of studies in ophthalmology in which it has been used. We also provide a problem/solution approach for limitations arising from the lists obtained from registers or other reliable sources.We concluded that capture-recapture models can be considered reliable to estimate the total number of cases with eye conditions using incomplete information from registers. Accordingly, the method may be used to maintain updated epidemiological information about eye conditions helping to tackle the lack of surveillance information in many regions of the globe.

Objectives: The aim of this study was to estimate the prevalence and causes of vision impairment (VI) in Portugal.

Setting Information about people with VI was obtained from primary care centres, blind association (ACAPO) and from hospitals (the PCVIP study) in the Northwest of Portugal during a period spanning years 2014–2015. Causes of VI were obtained from hospitals.

Participants Administrative and medical records of people with visual acuity in the better seeing eye of 0.5 decimal (0.30logMAR) or worse and/or visual field less than 20° were investigated. Capture–recapture with log-linear models was applied to estimate the number of individuals missing from lists of cases obtained from available sources.

Primary and secondary outcome measures Log-linear models were used to estimate the crude prevalence and the category specific prevalence of VI.

Results Crude prevalence of VI was 1.97% (95% CI 1.56% to 2.54%), and standardised prevalence was 1% (95% CI 0.78% to 1.27%). The age-specific prevalence was 3.27% (95% CI 2.36% to 4.90%), older than 64 years, 0.64% (95% CI 0.49% to 0.88%), aged 25–64 years, and 0.07% (95% CI 0.045% to 0.13%), aged less than 25 years. The female-to-male ratio was 1.3, that is, higher prevalence among females. The five leading causes of VI were diabetic retinopathy, cataract, age-related macular degeneration, glaucoma and disorders of the globe.

Conclusions The prevalence of VI in Portugal was within the expected range and in line with other European countries. A significant number of cases of VI might be due to preventable cases and, therefore, a reduction of the prevalence of VI in Portugal seems possible. Women and old people were more likely to have VI and, therefore, these groups require extra attention. Future studies are necessary to characterise temporal changes in prevalence of VI in Portugal.No data are available. Raw data can be requested from the first author.

Mål: Syftet med denna studie var att uppskatta förekomsten av och orsakerna till synnedsättning i Portugal.

Studieplats: Information om personer med VI erhölls från primärvårdscentraler, blindassociation (ACAPO) och från sjukhus (PCVIP-studien) i nordvästra Portugal under en period som sträckte sig över åren 2014–2015. Orsaker till synnedsättning erhölls från sjukhus.

Deltagare: Administrativa och medicinska journaler för personer med synskärpa i det bättre seende ögat på 0,5 decimal (0,30logMAR) eller sämre och/eller synfält mindre än 20° undersöktes. Capture-recapture med log-linjära modeller användes för att uppskatta antalet individer som saknas i listor över fall som erhållits från tillgängliga källor.

Primära och sekundära utfallsmått: Log-linjära modeller användes för att uppskatta den råa prevalensen och den kategorispecifika prevalensen av synnedsättning.

Resultat: Rå prevalens av synnedsättning var 1,97% (95% CI 1,56% till 2,54%), och standardiserad prevalens var 1% (95% CI 0,78% till 1,27%). Den åldersspecifika prevalensen var 3,27% (95% CI 2,36% till 4,90%), äldre än 64 år, 0,64% (95% CI 0,49% till 0,88%), i åldern 25–64 år och 0,07% (95% CI 0,045% till 0,13%), i åldern under 25 år. Förhållandet mellan kvinnor och män var 1,3, det vill säga högre prevalens bland kvinnor. De fem främsta orsakerna till synnedsättning var diabetisk retinopati, grå starr, åldersrelaterad makuladegeneration, glaukom och störningar i världen.

Slutsatser: Prevalensen av synnedsättning i Portugal låg inom det förväntade intervallet och i linje med andra europeiska länder. Ett betydande antal fall av synnedsättning kan bero på fall som kan förebyggas, och därför verkar en minskning av prevalensen av synnedsättning i Portugal möjlig. Kvinnor och gamla människor var mer benägna att ha synnedsättning och därför kräver dessa grupper extra uppmärksamhet. Framtida studier är nödvändiga för att karakterisera tidsmässiga förändringar i prevalensen av synnedsättning i Portugal.

*Detta abstrakt har maskinöversatts, osäkerheter kan uppstå

Objetivos: O objetivo deste estudo foi estimar a prevalência e as causas da deficiência visual em Portugal.

Local de realização do estudo: Informação sobre pessoas com deficiência visual foi obtida a partir de centros de cuidados primários, associação ACAPO e de hospitais (via estudo PCVIP) no Noroeste de Portugal durante um período que se estendeu entre 2014 e 2015. As causas do deficiência visual foram obtidas apenas nos hospitais.

Participantes: Foram investigados registos administrativos e médicos de pessoas com acuidade visual no melhor olho de 0,5 decimal (0,30logMAR) ou pior e/ou campo visual inferior a 20°. Foi aplicado o metodo de captura-recaptura com modelos log-linear para estimar o número de pessoas que não constavam em nenhuma das listas de casos obtidos a partir de fontes disponíveis.

Resultados primários e secundários: Foram utilizados modelos log-linear para estimar a prevalência bruta e a prevalência específica da deficiência visual.

Resultados: A prevalência bruta de deficiência visual foi de 1,97% (95% CI 1,56% para 2,54%), e a prevalência padronizada foi de 1% (95% 1,78% para 1,27%). A prevalência específica da idade foi de 3,27% (95% CI 2,36% a 4,90%), mais de 64 anos, 0,64% (95% CI 0,49% para 0,88%), com idades compreendidas entre os 25 e os 64 anos e 0,07% (95% CI 0,045% para 0,13%), com menos de 25 anos. A racio entre mulheres e homens foi de 1,3, ou seja, maior prevalência no sexo feminino. As cinco principais causas de deficiência visual foram a retinopatia diabética, catarata, degeneração macular relacionada com a idade, glaucoma e desordens do globo.

Conclusões: A prevalência de deficiência visual em Portugal estava dentro do intervalo esperado e em linha com outros países europeus. Um número significativo de casos de deficiência visual pode estar relacionados com causas evitáveis e, portanto, uma redução da prevalência de deficiência visual em Portugal parece possível. As mulheres e os idosos são mais propensos a ter deficiência visual e, por conseguinte, estes grupos exigem uma atenção extra. São necessários mais estudos para caracterizar as mudanças temporais na prevalência de deficiência visual em Portugal.

Purpose

Generic instruments to assess health utilities can be used to express the burden of health problems in widely used indexes. That is in contrast with what can be obtained with condition-specific instruments, outcomes are very specific and difficult to compare across conditions. The purpose of this study was to assess health and visual outcomes and its determinants in patients with visual impairment (VI) using the EQ-5D-3L and the Activity Inventory (AI).

Methods

Participants were recruited in different hospitals during the PCVIP-study. A total of 134 patients with acuity 0.30 logMAR or less in the better eye were interviewed. The AI includes 46 goals split between three objectives: social functioning, recreation and daily living, and was used to measure visual ability. The EQ-5D consists of five questions covering one domain each and was used to provide a measure of health states. Responses to each domain were combined to produce a single individual index.

Results

The AI and the EQ-5D-3L showed enough discriminatory power between VI levels (p < 0.001), and their results were strongly correlated r(134) = 0.825, (p < 0.001). Explanatory factors for visual ability were level of VI in better eye, age and gender, R² = 0.43, (p < 0.001). Explanatory factors for the EQ-5D-3L were level of VI in the better eye, comorbidities and gender, R² = 0.36, (p < 0.001).

Conclusion

Our results showed that the EQ-5D-3L is useful when characterizing the burden of VI and to compute, when necessary, quality-adjusted-life-years (QALY) changes due to VI. However, it is important to consider that the EQ-5D-3L uses a coarse response scale, assesses a limited spectrum of domains and is influenced by comorbidities. This might limit its responsiveness to small changes in visual ability.

Purpose

To estimate and characterize the use of informal care by people with vision impairment in Portugal.

Methods

A total of 546 visually impaired individuals were recruited from Portuguese hospitals. Clinical information was obtained from medical records, socio-demographic details and informal care use were collected during face-to-face interviews. In addition, participants responded to a functional vision questionnaire (activity inventory) to assess their visual ability. Logistic regression was used to determine independent factors associated with informal care use and linear regression was used to determine independent predictors of intensity of informal care use.

Results

Informal care was reported by 39.6% of the participants. The probability of reporting informal care was higher in non-married, those with comorbidities, with lower visual ability and worse visual acuity. The median number of caregivers’ hours per year was 390 (mean = 470; 95%CI = 488–407), which represent a median opportunity cost of €2,586. Visual ability was the only independent predictor of number of hours of informal care received.

Conclusions

Informal care was frequently used by individuals with impaired vision. Improving visual ability of people with impaired vision when performing valued activities may reduce the burden of visual loss at personal and societal level. This could be achieved with person-centred visual rehabilitation.

Purpose: To estimate productivity losses amongst people with impaired vision in Portugal and to investigate explanatory factors associated with non-participation in the labour market.

Methods: A total of 546 visually impaired individuals participated in face-to-face interviews. Participants were asked about their workforce participation to determine productivity (employment status questionnaire), their health-related quality of life – HRQoL (EQ-5D) and their visual acuity and visual ability (Activity Inventory). Productivity losses included absenteeism and reduction in workforce participation. Logistic regression was used to determine independent factors associated with participation in the labour market.

Results: From the 546 participants, 50% were retired, 47% were of working age and 3% were students. The employment rate was 28%, and the unemployment rate was 21% for the working age sample. For those of working age, productivity losses were estimated at €1.51 million per year, mean of €5496 per participant. The largest contributor to productivity losses was reduced workforce participation, estimated from 159 early retired or unemployed participants. After controlling for visual acuity and ability, younger individuals, with more years of education, without comorbidities and high HRQoL had a higher probability of being employed.

Conclusions: Our findings show a high unemployment rate and high productivity losses amongst people with impaired vision. The probability of being employed was associated with education, HRQoL and comorbidities. We speculate that promoting education and health through effective visual rehabilitation programs may help to increase participation in the labour market. These findings can inform decisions to intervene to reduce the burden of vision loss.

Abstract Purpose To investigate the cost-effectiveness of a basic vision rehabilitation service (basic-VRS) in Portugal. We designed a parallel group, randomised controlled trial whose aim is to compare the effects and costs of ?usual low vision care? with a ?basic-VRS intervention? on self-reported visual ability and other psychosocial and health-related quality-of-life outcomes. Methods The trial will recruit participants that meet the following inclusion criteria: (1) visual acuity between 0.4?1.0 logMAR in the better-seeing eye, (2) cause of vision loss is diabetic retinopathy or age-related macular degeneration, (3) 18 years or older and iv) live in the community (not in nursing homes or other type of institution). Participants will be randomised to one of the study arms consisting of immediate intervention and delayed intervention. The delayed intervention group will receive ?usual care? or no intervention in the first 12 weeks. Visual acuity, contrast sensitivity and retinal structure will be assessed during the study. Results The primary outcome measure is visual ability, which will be evaluated with the Massof Activity Inventory, we expect that the intervention will raise the overall person measure or visual ability. Reading, health-related quality-of-life, anxiety and depression and social support will be also assessed. The analysis will be undertaken on an intention-to-treat basis. A cost-effectiveness analysis will be performed to provide information about the cost per unit of utility. To evaluate the cost-effectiveness of the intervention we will adopt the perspective of the healthcare system. Conclusion This study will provide additional evidence about the effects of basic-VRS on self-reported visual ability. Findings from this study should also contribute to better planning of low vision provision and, consequently, may contribute to reduce barriers to basic-VRS.