Point: Immortal Time Bias-What Are the Determinants of Its Magnitude?

In cohort studies, "immortal time" bias refers to a portion of time during which events cannot occur for a particular group of participants. Typically, immortal time bias occurs when: 1) Exposure can be initiated after follow-up of cohort members has begun; and 2) analytically, the preexposure experience is combined with that which takes place following exposure, rather than (correctly) as part of the experience of nonexposed individuals. Using the example of a cohort study of mortality in relation to receipt of cataract surgery, we sought to describe those study design and population characteristics that influence the magnitude of immortal time bias, so as to aid readers in gauging its impact on published research findings. These characteristics include the mean interval between cohort entry and when exposure criteria are met, the proportion of exposed study participants, and the length of study follow-up.

Association of Mortality with Ocular Diseases and Visual Impairment in the Age-Related Eye Disease Study 2: Age-Related Eye Disease Study 2 Report Number 13.

PURPOSE: To evaluate the association of mortality with visual acuity (VA) impairment, age-related macular degeneration (AMD), and cataract surgery. DESIGN: Cohort study. PARTICIPANTS: Participants with at least intermediate AMD enrolled in a randomized controlled clinical trial of lutein/zeaxanthin and/or omega-3 fatty acids, the Age-Related Eye Disease Study 2 (AREDS2), for treatment of AMD and cataract. METHODS: Baseline and annual eye examinations included best-corrected visual acuity (BCVA) assessments, slit-lamp examinations, and stereoscopic fundus photographs that were centrally graded for development of late AMD (central geographic atrophy or neovascular AMD) or pseudophakia. Cause-specific mortality was determined on the basis of the International Classification of Diseases 9th or 10th Revision codes. Risk of all-cause and cause-specific mortality was assessed with Cox proportional hazards models adjusted for age, sex, AMD severity, VA, history of cataract surgery, and assigned AREDS2 study treatment. Analyses included baseline covariates: race, education, smoking status, diabetes, and cardiovascular disease. RESULTS: During follow-up (median 5 years), 368 (9%) of the 4203 AREDS2 participants died. Participants with neovascular AMD in 1 eye at baseline had a statistically significant increased risk for mortality compared with participants with no or few drusen (hazard ratio [HR], 1.56; 95% confidence interval [CI], 1.21-2.01; P < 0.001). Poorer survival was associated with bilateral cataract surgery before enrollment compared with baseline bilateral phakia (HR, 1.63; 95% CI, 1.29-2.07; P < 0.001) and with BCVA of less than 20/40 compared with participants with 20/40 or better (HR, 1.56; 95% CI, 1.06-2.30; P = 0.024), adjusted for age, sex, and statistically significant covariates. Participants who received antivascular endothelial growth factor therapies for neovascular AMD had decreased mortality compared with those who did not (HR, 0.71; 95% CI, 0.57-0.88; P = 0.002). The association between all-cause mortality and AREDS2 treatment whether assessing the main or individual treatment effect was not significantly different (omega-3 fatty acids main effect HR, 1.18; 95% CI, 0.96-1.45; P = 0.12; lutein/zeaxanthin main effect HR, 1.04; 95% CI, 0.85-1.28; P = 0.71). CONCLUSIONS: In AREDS2, the presence of late AMD, bilateral cataract surgery, and VA less than 20/40 was associated with decreased survival. However, oral supplementation with omega-3 fatty acids, lutein plus zeaxanthin, zinc, or beta-carotene had no statistically significant impact on mortality.

Association of Cataract Surgery With Mortality in Older Women: Findings from the Women's Health Initiative.

Importance: Previous studies have suggested an association between cataract surgery and decreased risk for all-cause mortality potentially through a mechanism of improved health status and functional independence, but the association between cataract surgery and cause-specific mortality has not been previously studied and is not well understood. Objective: To examine the association between cataract surgery and total and cause-specific mortality in older women with cataract. Design, Setting, and Participants: This prospective cohort study included nationwide data collected from the Women's Health Initiative (WHI) clinical trial and observational study linked with the Medicare claims database. Participants in the present study were 65 years or older with a diagnosis of cataract in the linked Medicare claims database. The WHI data were collected from January 1, 1993, through December 31, 2015. Data were analyzed for the present study from July 1, 2014, through September 1, 2017. Exposures: Cataract surgery as determined by Medicare claims codes. Main Outcomes and Measures: The outcomes of interest included all-cause mortality and mortality attributed to vascular, cancer, accidental, neurologic, pulmonary, and infectious causes. Mortality rates were compared by cataract surgery status using the log-rank test and Cox proportional hazards regression models adjusting for demographics, systemic and ocular comorbidities, smoking, alcohol use, body mass index, and physical activity. Results: A total of 74 044 women with cataract in the WHI included 41 735 who underwent cataract surgery. Mean (SD) age was 70.5 (4.6) years; the most common ethnicity was white (64 430 [87.0%]), followed by black (5293 [7.1%]) and Hispanic (1723 [2.3%]). The mortality rate was 2.56 per 100 person-years in both groups. In covariate-adjusted Cox models, cataract surgery was associated with lower all-cause mortality (adjusted hazards ratio [AHR], 0.40; 95% CI, 0.39-0.42) as well as lower mortality specific to vascular (AHR, 0.42; 95% CI, 0.39-0.46), cancer (AHR, 0.31; 95% CI, 0.29-0.34), accidental (AHR, 0.44; 95% CI, 0.33-0.58), neurologic (AHR, 0.43; 95% CI, 0.36-0.53), pulmonary (AHR, 0.63; 95% CI, 0.52-0.78), and infectious (AHR, 0.44; 95% CI, 0.36-0.54) diseases. Conclusions and Relevance: In older women with cataract in the WHI, cataract surgery is associated with lower risk for total and cause-specific mortality, although whether this association is explained by the intervention of cataract surgery is unclear. Further study of the interplay of cataract surgery, systemic disease, and disease-related mortality would be informative for improved patient care.

Cataract-Related Visual Impairment Corrected by Cataract Surgery and 10-Year Mortality: The Liwan Eye Study.

PURPOSE: To assess 10-year mortality in people who had undergone cataract surgery with no residual visual impairment (VI) and those who had persistent VI due to cataract using a population-based cohort. METHODS: The Liwan Eye Study is a 10-year longitudinal study commenced in 2003. According to the World Health Organization, presenting VI was defined as visual acuity less than 20/63 in the better-seeing eye. History of cataract surgery was defined as cataract surgery performed on either eye. Information on the date of surgery was recorded. Dates of death occurring between baseline and April 30, 2014 were obtained from the National Death Index data. Information on socioeconomic factors was obtained from questionnaire interviews. Cox proportional hazards regression models were used to assess the hazard ratios (HRs) and 95% confidence intervals (CIs). RESULTS: Fifty-nine participants had undergone cataract surgery without residual VI and 67 participants had persistent cataract-related VI. The 10-year mortality rate for participants who had undergone cataract surgery without residual VI was statistically significant lower than that in participants who had VI due to cataract based on log-rank test (32.2% vs. 64.2%; P = 0.002). This finding remained significant in the unadjusted Cox proportional hazards model (HR, 0.43; 95% CI, 0.25-0.74; P = 0.002). After adjusting for age, sex, history of diabetes, and hypertension, body mass index (BMI), education level, and personal income, participants with cataract surgery and no residual VI did not have a higher chance of survival than participants with persistent VI due to cataract (HR, 0.56; 95% CI, 0.26-1.20; P = 0.136). CONCLUSIONS: Cataract-related VI corrected by cataract surgery was not associated with better survival after adjusting for a number of possible confounders. Given our sample size is relatively small and limited power, further studies with larger sample are needed.

Cataract Surgery and Mortality in the United States Medicare Population.

PURPOSE: To determine the association between cataract surgery and all-cause mortality in United States Medicare patients with cataract. DESIGN: Retrospective cohort study. PARTICIPANTS: A 5% random sample of United States Medicare beneficiaries with a diagnosis of cataract from the 2002 through 2012 Denominator and Physician/Supplier Part B files. METHODS: The exposure of interest was cataract surgery and the outcome of interest was all-cause mortality. Baseline characteristics that were examined included demographics, systemic comorbidities, and ocular comorbidities. Cox proportional hazards regression modeling was used to assess the association between cataract surgery and mortality. Additional subgroup analyses were performed in propensity score deciles and within strata of age, gender, region, systemic disease burden, and in patients with versus without severe cataract subtypes. MAIN OUTCOME MEASURES: All-cause mortality. RESULTS: The 5% Medicare sample included 1 501 420 patients with cataract, of whom 544 984 (36.3%) underwent cataract surgery. Patients with cataract surgery were followed up for a mean of 11.4 quarters (standard deviation [SD], 10.8 quarters; range, 0.0-44.0 quarters), whereas patients without cataract surgery were followed up for a mean of 12.9 quarters (SD, 12.2 quarters; range, 0.0-44.0 quarters). Mortality incidence was 2.78 deaths per 100 person-years in patients with cataract surgery and 2.98 deaths per 100 person-years in patients without surgery (P < 0.0001). Overall, patients with cataract surgery had a lower adjusted hazard of mortality compared with patients without surgery (hazard ratio [HR], 0.73; 95% confidence interval [CI], 0.72-0.74). The strongest associations were observed in patients with a high propensity score decile (HR, 0.52; 95% CI, 0.50-0.54), patients 80 to 84 years of age (HR, 0.63; 95% CI, 0.62-0.65), women (HR, 0.69; 95% CI, 0.68-0.70), patients in the western United States (HR, 0.52; 95% CI, 0.32-0.86), patients with a moderate systemic disease burden (HR, 0.71; 95% CI, 0.69-0.72), and patients with severe cataract (HR, 0.68; 95% CI, 0.66-0.70). CONCLUSIONS: In a national cohort of United States Medicare beneficiaries with cataract, cataract surgery was associated with decreased all-cause mortality. Further studies are needed to examine mechanisms surrounding the association between cataract surgery and mortality.

Epidemiology of 411 140 cataract operations performed in public hospitals and private hospitals/clinics in Denmark between 2004 and 2012.

PURPOSE: To study the epidemiology and mortality in patients who had cataract surgery in public hospitals and private hospitals/clinics in Denmark between 2004 and 2012 and to assess the validity of the Danish cataract registries. METHODS: Register- and chart-based study. RESULTS: A total of 411 140 cataract operations were performed in 243 856 patients. Patients who had cataract surgery in public hospitals had an overall statistically significantly 62% higher mortality compared to patients who had cataract surgery in private hospitals/clinics. The decrease in mean age at first eye cataract surgery in private hospitals/clinics was statistically significantly greater compared to the decrease in mean age at first eye cataract surgery in public hospitals (p < 0.001). The median time interval between first and second eye cataract surgery decreased statistically significantly during the study period (p < 0.001) and was statistically significantly shorter in all calendar years for patients operated in private hospitals/clinics compared to patients operated in public hospitals (p < 0.001). In all, 46% of the cataract operations performed in private hospitals/clinics that led to cases of postoperative endophthalmitis were not registered in any registry. CONCLUSION: In general, patients who had cataract surgery in private hospitals/clinics were healthier, had first eye cataract surgery at an increasingly younger age and had a reduced time interval between cataract surgeries in the two eyes compared to patients who had cataract surgery in public hospitals. The lack of registration of cataract surgery by the private hospitals/clinics limits the quality of the registries.

Short-term mortality following cataract surgery: comparison of Veterans Health Administration and Medicare outcomes.

PURPOSE: To compare short-term risk of death following cataract surgery in veterans having surgery in the Veterans Health Administration (VHA) and through Medicare. METHODS: Medicare and VHA databases were merged to identify a cohort of veterans (N = 149,023) that had outpatient cataract surgery during 2007. National mortality sources were used to ascertain vital statistics. A Cox regression model estimated hazard ratios for routine and complex cataract extractions. RESULTS: Ninety days after cataract surgery the rates of death were 0.80% for patients in Medicare and 0.70% for beneficiaries in the VHA (P > 0.05). There was no difference in death hazard 6 months following surgery, after adjusting for age, race, gender, and medical comorbidities. Significant Medicare hazard ratio (HR) was seen at one year with routine cataract extraction (HR 1.17, 95% confidence interval, CI, 1.09-1.27), and with complex cataract extraction (HR 1.17, 95% CI 1.08-1.27). CONCLUSIONS: The 6-month risk of death after cataract surgery is low, and does not differ among veterans whose surgery was performed in the VHA or through Medicare. If confirmed, excess postoperative mortality at one year in Medicare needs to be studied through more direct methodologies.

Predictors of mortality within 90 days of cataract surgery.

PURPOSE: To identify predictors of mortality within 90 days of cataract surgery. DESIGN: A retrospective cohort study. PARTICIPANTS: A total of 45,082 patients who underwent cataract surgery in the Veterans Health Administration (VHA) between October 1, 2005 and September 30, 2007. METHODS: The National Patient (US) Care Database (NPCD) was used to identify all patients who underwent outpatient extracapsular cataract surgery performed in the VHA and who had only 1 cataract surgery within 90 days of the index surgery. Data collected includes demographics, number of hospitalizations within 1 year before surgery, postoperative mortality, and systemic comorbidities using the Charlson Comorbidity Index (CCI), which predicts the 1-year mortality for a patient based on a range of co-morbid conditions scored 1, 2, 3 or 6 depending on the risk of dying associated with the condition. Adjusted odds ratios (OR) of factors predictive of 90-day mortality were calculated using logistical regression modeling. MAIN OUTCOME MEASURES: Mortality within 90 days of cataract surgery. RESULTS: Of the 53,786 patients who underwent cataract surgery during the study period, 45,082 met inclusion criteria. Mean age was 71.8 years; 97.6% were men; 5.0% had complex cataract surgery. The most frequent systemic comorbidities in the CCI were diabetes mellitus (40.6%), chronic pulmonary disease (21.2%), malignant neoplasms (12.5%) and congestive heart failure (CHF; 9.5%). Patients had a median CCI score of 1; 43.7% had a score ≥ 2. Mortality rate within 90 days after cataract surgery was 7.1 per 1000 patients. Independent predictors of 90-day postoperative mortality were [adjusted OR, (95% confidence interval; CI)]: age 80 or greater [2.54 (1.62, 3.98)], CCI ≥ 2 [2.06 (1.58, 2.70)], ≥ 1 hospitalizations in the past year [1.85 (1.45, 2.36)], chronic pulmonary disease (CPD) [1.69 (1.34, 2.14)], CHF [1.71 (1.29, 2.14)], cirrhosis [2.60 (1.31, 5.15)], multiple myeloma or leukemia [2.20 (1.07, 4.53)], and metastatic solid tumor [4.17 (1.80, 9.66)]. CONCLUSIONS: The risk of 90-day mortality after cataract surgery is low, even for patients at higher risk for mortality such as the elderly and those with a high preoperative disease burden.

Is there a relationship between physician and facility volumes of ambulatory procedures and patient outcomes?

This study explores associations between patient outcomes (7- and 30-day hospitalization and mortality) and healthcare provider (physician and facility) volumes of outpatient colonoscopy, cataract removal, and upper gastrointestinal endoscopy performed in outpatient surgical settings in Florida. Findings indicate that patients treated by high-volume physicians or facilities had lower adjusted odds ratios for hospitalizations and mortality. When physician and facility volume were assessed simultaneously, physician volume accounted for larger effects than facility volume in hospitalization models. When assessing both physician and facility volume together for mortality, facility volume was a stronger predictor of mortality outcomes at 30 days. Further examinations of associations of outpatient physician and facility volumes and patient outcomes are suggested.

Associations of mortality with ocular disorders and an intervention of high-dose antioxidants and zinc in the Age-Related Eye Disease Study: AREDS Report No. 13.

OBJECTIVE: To assess the association of ocular disorders and high doses of antioxidants or zinc with mortality in the Age-Related Eye Disease Study (AREDS). METHODS: Baseline fundus and lens photographs were used to grade the macular and lens status of AREDS participants. Participants were randomly assigned to receive oral supplements of high-dose antioxidants, zinc, antioxidants plus zinc, or placebo. Risk of all-cause and cause-specific mortality was assessed using adjusted Cox proportional hazards models. RESULTS: During median follow-up of 6.5 years, 534 (11%) of 4753 AREDS participants died. In fully adjusted models, participants with advanced age-related macular degeneration (AMD) compared with participants with few, if any, drusen had increased mortality (relative risk [RR], 1.41; 95% confidence interval [CI], 1.08-1.86). Advanced AMD was associated with cardiovascular deaths. Compared with participants having good acuity in both eyes, those with visual acuity worse than 20/40 in 1 eye had increased mortality (RR, 1.36; 95% CI, 1.12-1.65). Nuclear opacity (RR, 1.40; 95% CI, 1.12-1.75) and cataract surgery (RR, 1.55; 95% CI, 1.18-2.05) were associated with increased all-cause mortality and with cancer deaths. Participants randomly assigned to receive zinc had lower mortality than those not taking zinc (RR, 0.73; 95% CI, 0.61-0.89). CONCLUSIONS: The decreased survival of AREDS participants with AMD and cataract suggests that these conditions may reflect systemic rather than only local processes. The improved survival in individuals randomly assigned to receive zinc requires further study.

The association between cataract and mortality among older adults.

CONTEXT: Previous research has suggested that persons with cataract have an increased risk of death. OBJECTIVE: To compare the mortality experience of patients with cataract who elect surgery, patients with cataract who do not elect surgery, and patients without cataract independent of potentially confounding risk factors. DESIGN: Cohort study. SETTING: Ophthalmology and optometry clinics affiliated with the Callahan Eye Foundation Hospital in Birmingham, Alabama. PATIENTS: 384 persons with and without cataract. MAIN OUTCOME MEASURE: Mortality. RESULTS: Of the 384 study subjects, 286 had cataract, of whom 200 elected to have cataract surgery. Patients with cataract who did and did not elect surgery had significantly higher mortality compared to those without cataract (crude mortality rate ratio (MRR) 3.9 (95% confidence interval (CI) 1.5-9.8) and 7.3 (95% CI 2.8-19.1), respectively). After adjustment for age, gender, race, education, chronic medical conditions, smoking, drinking, depression, and cognitive status, the no-surgery cataract group had an elevated mortality rate (MRR 3.2 (95% 1.2-9.0)), compared to the no-cataract group, with a borderline elevation in MR for the surgery group (MRR 2.0 (95% 0.8-5.9). Limiting the study population to non-diabetics or those without concurrent eye conditions (glaucoma, maculopathy, retinopathy) did not materially influence the adjusted MRRs although the precision of the estimates was reduced. CONCLUSIONS: The results suggest that older persons with cataract, in particular those who decline surgery, have an increased risk of death, supporting the hypothesis that age-related cataract reflects systemic as well as localized ocular disease.

Cataracts associated with systemic disorders and syndromes.

This review article examines the ophthalmic literature published on cataracts and systemic disease during the past year. Epidemiologically, the association between alcohol consumption and lens opacification is reviewed. Cataracts continue to be strongly associated with systemic diseases such as diabetes mellitus. Clinical, basic science reports and the results of the Blue Mountains Eye Study group on the morphology of diabetes-related cataracts are presented. Patients with neurologic disorders such as Wilson disease may first present with decreased vision and cataracts. Cataracts are now associated with syndromes such as Cohen syndrome, Degos disease, and Dubowitz syndrome. A recent study suggests earlier mortality in middle-age patients undergoing cataract surgery.

The effects of introducing prospective payments to general hospitals on length of stay, quality of care, and hospitals' income: the early experience of Israel.

A new reimbursement system for general hospitals in Israel was introduced in July 1990. The new system specified that for 15 selected procedures, hospitals would be paid by the insurers prospectively, rather than by the traditional per-diem arrangement. The rates were determined by the Ministry of Health. Henceforth, the number of selected procedures has increased and by now 40 procedures are included. In line with the ever-lasting interest in the effect of financial incentives on suppliers of medical care, the purpose of this paper is to examine the first-year effect of this change on the volume of activity, length of stay, quality of care, and hospitals' real income. We focused on five selected procedures (cholecystectomy, hysterectomy, hip replacement, operations on lens and heart surgeries) performed in the four largest Israeli medical centers (Sheba, Sorasky, Rambam, and Hadassah). The analysis includes more than 17,000 hospitalizations occurring during two years prior to the change (July 1988-June 1990) and the first year after its implementation (July 1990-June 1991). We, therefore, examined, the short-term effects, wherein changes in the hospitals' behavior are reflected mainly in the above-mentioned hospitalization characteristics. Further analysis will be required to examine the long-run implications of the change as well as its effect on the rest of the general inpatient sector in Israel.

Assessing health-related quality of life in cataract patients: the relationship between utility and health-related quality of life measurement.

The relationship between health-related quality of life (HQL) measures and patient preference for their health status was studied. Study subjects consisted of 132 patients at four hospitals who were scheduled for cataract surgery. Generic and disease-specific health status measures were determined in study subjects. The Medical Outcomes Study Short-form 36 (SF-36) item health status instrument was used to measure generic health status and the Visual Function 14 (VF-14) item visual health status instrument was used as the disease-specific health measure. Preference for general health and visual health was measured by assessing utilities assigned by patients to certain health states. Utilities assigned for general health were correlated with all categories of the SF-36 and VF-14 scores. Utilities assigned for visual health were correlated with four categories of the SF-36 (role limitation due to emotional health, general health, physical functioning, and vitality) and VF-14 scores. Utilities assigned for visual health were more strongly correlated with VF-14 scores than generic measures of health. Verbal ratings for visual health were correlated with Snellen visual acuity (SVA) (r = 0.20), utilities assigned for visual health (r = 0.58), VF-14 scores (r = 0.74), all categories of the SF-36 (r values ranging from 0.21 to 0.28), utilities assigned for general health (r = 0.19), and verbal ratings for general health (r = 0.29). Utility measures and verbal ratings for general and visual health were shown to be appropriate HQL measures. These measures were strongly correlated with other established generic and disease-specific health measures and should be included in the array of health status measures.

Mortality rates after cataract extraction.

Senile cataract may be a marker of generalized tissue aging. We examined this hypothesis using population-based linked health data. We hypothesized that any such association would diminish with increased use of cataract surgery. Mortality rates of those 50-95 years of age undergoing cataract surgery in British Columbia during either 1985 or 1989 were compared with the provincial population of comparable age who did not undergo cataract surgery during the study period. The 1985 cohort included 8,262 patients undergoing surgery and a comparison population of 804,303, and the 1989 cohort included 11,952 patients and a comparison population of 839,393. Using Cox regression, for the 1985 cohort, the hazard ratios for dying during follow-up were 3.2 for males 50-54.9 years of age [95% confidence limits (CL) = 2.0, 5.0] and 3.3 for females (95% CL = 1.9, 5.7). Hazard ratios for older age groups decreased with age. We also fit an additive risk model that produced excess mortalities that were less age dependent. In the 1985 analysis, these ranged from +7.1 per 1,000 (95% CL = +0.44, +13.76) to +20.3 (95% CL = +13.24, +27.36) for males and -17.5 (95% CL = -28.28, -6.72) to +2.0 (95% CL = -2.12, +6.12) for females. Findings for the 1989 analyses were similar, indicating that the association between cataracts and generalized aging remained constant despite a large increase in the use of cataract surgery.

Mortality and causes of mortality among cataract-extracted patients. A 10-year follow-up.

PURPOSE: The purpose of this study was to compare the mortality among patients undergoing intracapsular cataract extraction to the mortality in a gender-and age-identical Danish reference population, and to compare the patients' primary causes of death to those in the general population. MATERIALS AND METHODS: We reviewed medical records of patients undergoing ICCE from January 1st 1984 to December 31st 1986 at the Department of Ophthalmology, Aalborg Hospital, Denmark. Information on the deaths of these patients was obtained from the Danish National Population Register. Information on mortality in Denmark was obtained from published statistics. RESULTS: We found an increased mortality among the patients with cataract with an SMR (standard mortality rate) of 1.12 (95% confidence interval 1.02-1.23). The slightly increased mortality was observed for both men and women and for all examined causes of death. CONCLUSION: The slightly increased mortality among patients with cataract may indicate a general deterioration of health for these patients.

Cataract patients in a defined Swedish population 1986-90: VII Inpatient and outpatient standardised mortality ratios.

AIMS: Cataract surgery has at times been said to correlate with an increased death risk. We have therefore analysed the standardised death ratio in a population based cohort of patients that had undergone cataract surgery. METHODS: Data for all patients undergoing cataract surgery from 1986 up to and including 1990 in the Lund Health Care District were prospectively recorded, and 5120 were retrieved for analysis. Death dates and primary death diagnoses for each patient were obtained from the Swedish Bureau of Census up to and including 1991. Standardised mortality ratios were calculated for all patients, subdivided into a number of categories: inpatients, outpatients, sex, age < 75 years, age > or = 75 years, patients with heart and circulatory diseases, with malignant tumours, and with diabetes. The cut off age was set at 74 because this divided the patients into two approximately equal groups. Using time dependent survival regression, the relative risk for dying were estimated for sex, age, and for postoperative YAG laser capsulotomy, and also for diabetic patients and patients with rheumatoid arthritis. RESULTS: Inpatients almost always show an increased standardised mortality ratio compared with outpatients. Young patients and diabetic patients also showed an increased standardised mortality ratio, compared with the normal population, but not older patients, who constitute the majority. Cardiovascular death diagnoses were overrepresented among the young. CONCLUSIONS: Cataract surgery is correlated with an increased standardised mortality ratio only in young patients and in patients with certain complicating diseases like diabetes and cardiovascular diseases.

National five-year mortality after inpatient cataract extraction.

We assessed the five-year mortality in all United States Medicare beneficiaries aged 65 to 79 years who underwent inpatient cataract extraction in 1984. The risk of dying within five years after cataract extraction was compared to the five-year mortality risk of the same aged persons in the United States population. Patients with cataracts who were younger than 75 years had significantly higher age-specific rates of mortality than would be predicted from United States life tables (P less than .001). For example, at the age of 65 years, patients with cataracts had 1.34 times the risk of the United States population (95% confidence interval = 1.29 to 1.41). This risk progressively declined until the age of 75 years, at which age there is little difference between the patients with cataracts and the United States population, except for the oldest women with cataracts (at the age of 79 years, relative risk = .90; 95% confidence interval = .82 to .99). Although selection factors may account for the excess mortality observed among these individuals, these data do support previous analyses that suggest an association between senile cataract and increased risk of mortality.