- Email: [email protected]
Determinants of glaucoma awareness in a general eye clinic1
Determinants of Glaucoma Awareness in a General Eye Clinic Alice T. Gasch, MD,1 Philip Wang, MD, Dr PH,2 Louis R. Pasquale, MD1,3 Purpose: Heightened public awareness about glaucoma may increase the chance of identifying undetected cases. To ascertain determinants of glaucoma awareness, we surveyed a population visiting a general eye clinic. Design: Cross-sectional study. Participants: 1197 general eye clinic patients and their companions. Methods: We designed and administered a questionnaire about glaucoma to general eye clinic patients and their companions. We created multivariate logistic regression models to ascertain the effect of demographic and clinical features on the likelihood of being unaware of glaucoma. Main Outcome Measures: Adjusted odds ratio (OR) with 95% confidence intervals of survery attributes associated with self-perceived unfamiliarity with glaucoma. Results: Glaucoma awareness overall (72%) approached that found in the subgroup self-reporting a diagnosis of glaucoma (80%). Survey attributes associated with an increased likelihood of being unaware of glaucoma were African American race (OR ⫽ 1.69 [1.28 –2.20], Hispanic ethnicity (OR ⫽ 2.13 [1.46 –3.02]), and less than a college education (OR ⫽ 1.67 [1.37–2.05]). Age was also a determinant of glaucoma awareness (for ages 50 – 64 years, OR ⫽ 0.60 [0.44 – 0.80] and for ages 65–79 years, OR ⫽ 0.56 [0.41– 0.75] compared with ages less than 35 years). A self-report of glaucoma was not a determinant of glaucoma awareness (OR ⫽ 0.63 [0.33–1.17]), although there was a trend toward enhanced glaucoma awareness in this subgroup. Finally, respondents with a history of employment in the health field (OR ⫽ 0.63 [0.49 – 0.82]) myopia (OR ⫽ 0.68 [0.56 – 0.82]), glaucoma in a first-degree relative (OR ⫽ 0.68 [0.53– 0.87]), and respondents who reported having a dilated eye examination (OR ⫽ 0.53 [0.42– 0.66]) were less likely to be unaware of glaucoma than those who did not have these attributes. Conclusions: Although glaucoma awareness in this population was high, Hispanics, African Americans, and those with less than a college education were more likely to be unfamiliar with the disease. Interestingly, a self-report of having glaucoma was not a statistically significant determinant of glaucoma awareness. Ophthalmology 2000;107:303–308 © 2000 by the American Academy of Ophthalmology. Glaucoma is a major public health problem. It is the second most common cause of legal blindness in the United States and the principal cause of legal blindness among African Americans.1 Approximately 80,000 Americans are legally blind from glaucoma,2 and many others are visually impaired from the disease. Extrapolating from Baltimore Eye Survey data, about 2 million Americans have primary openangle glaucoma, the most common type of glaucoma, yet
Originally received: May 3, 1999. Accepted: September 29, 1999. Manuscript no. 99213. 1 Massachusetts Eye and Ear Infirmary, Boston, Massachusetts. 2 Division of Pharmacoepidemiology and Pharmacoeconomics, Brigham and Women’s Hospital, Boston, Massachusetts. 3 Division of Ophthalmology, Brigham and Women’s Hospital, Boston, Massachusetts. Presented at the annual meeting of ARVO, Ft. Lauderdale, Florida, May, 1999. No financial support was received for this study. The authors have no proprietary or financial interest in any products used in this study. Reprint requests to Louis R. Pasquale, MD, Glaucoma Consultation Service, Massachusetts Eye and Ear Infirmary, 243 Charles St, Boston, MA 02114. © 2000 by the American Academy of Ophthalmology Published by Elsevier Science Inc.
only about half of them are aware that they have the disease.3 Visual loss resulting from glaucomatous optic neuropathy has a negative impact on a variety of visually oriented tasks necessary to function independently in society.4 – 6 This is of special concern because of the present trend toward dissolution of the nuclear family. Eye health education that influences individuals to participate in regular ophthalmologic care may be an important means of detecting glaucoma early, thereby preventing needless visual impairment and preserving quality of life.7 Celebrate Sight (formerly known as Glaucoma 2001) represents one strategy to increase glaucoma awareness by educating primary caregivers and the public about the disease. To most efficiently use resources to enhance public awareness about glaucoma, subgroups of the population that are at highest risk for both developing the disease and having insufficient knowledge about it need to be identified and targeted. Several studies have examined knowledge and/or beliefs about glaucoma in general clinic or population-based samples,8 –12 (Pfeiffer N, Krieglstein GK. Invest Ophthalmol Vis Sci 1993); 34 [Suppl]: 1192, but there never has been a ISSN 0161-6420/00/$–see front matter PII S0161-6420(99)00076-7
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Ophthalmology Volume 107, Number 2, Feburary 2000
Figure 1. Questionnaire.
comparable large-scale analysis conducted in a US urban center. Previous surveys conducted in a US rural center, England, Australia, and Germany indicate that 7% to 70% of participants report they are unfamiliar with glaucoma.8 –11 (Pfeiffer N, Krieglstein GK. Invest Opthalmol Vis Sci 1993); 34 [Suppl]: 1192. Analysis of these data indicates that age,8 family history of glaucoma,11 and education8,10,11 are determinants of glaucoma awareness. To the best of our knowledge, no prior study of glaucoma awareness evaluated race or ethnicity as a predictor of glaucoma awareness. Therefore, we assessed the relation between various demographic and clinical features and glaucoma awareness in a large, urban general eye clinic.
304
Materials and Methods A questionnaire (Fig. 1) was randomly distributed during a 4-month period in 1998 to nonconsecutive patients and their companions at the General Eye Service at the Massachusetts Eye and Ear Infirmary. No individuals were excluded from participation in the study on the basis of age. Those unable to write or communicate in English were excluded from the study. Less than 2% of individuals approached to participate in the study declined to do so. Respondents were not prompted to possible responses. No distributed questionnaire was excluded from analysis. No patient identifiers were maintained after the survey was completed. The Human Studies Committee of the Massachusetts Eye and Ear Infirmary approved the study. We calculated the sample size on the
Gasch et al. 䡠 Determinants of Glaucoma Awareness basis of having an 80% chance of identifying an attribute associated with glaucoma awareness, assuming that the attribute was present in 5% of the sample. In estimating our sample size, we aimed to detect a 15% difference in study attributes when the sample was stratified by glaucoma awareness. Other assumptions in our sample size calculation include a type I error of 0.05 and a 20% variance in survey attributes in the sample. The questionnaire was designed to capture information about demographics, risk factors for primary open-angle glaucoma, and awareness of glaucoma. It was designed to be brief, with most questions requiring “yes” or “no” answers. Questions related to family history of glaucoma also provided the option of “don’t know” as a response. Questions related to family history of glaucoma purposely were repeated for parents, siblings, and other relatives to enhance recall of a possible positive response. The questions were modified slightly after pilot administration to lay staff at the Massachusetts Eye and Ear Infirmary. Because there is consensus among previous studies that less educated individuals are more likely to be unaware of glaucoma,8,10,11 we used this question to validate our assessment of glaucoma awareness. Univariate analysis of the first 10% and first 30% of surveys showed a strong positive association between education and glaucoma awareness (data not shown). In performing statistical analysis of the overall data, we initially examined the proportion of subjects claiming awareness of glaucoma within the entire study population and within strata defined by demographic and clinical features. We also assessed the proportion of subjects in the entire study population and within strata, who endorsed other survey questions. Crude relationships between demographic or clinical variables and glaucoma awareness were explored with chi-square statistics. To examine the independent effects of demographic and clinical variables on the likelihood of being unaware of glaucoma, we constructed several multivariate logistic regression models. Age, gender, and race were included in the models as categorical variables. Age also was used as a continuous variable in modeling the data. Remaining demographic and clinical variables then were subjected to a forward stepwise selection procedure in which variables significantly associated with the outcome at the p ⱕ 0.2 level were included. Adjusted odds ratios and the associated 95% confidence intervals for attributes that are independent predictors of glaucoma awareness at the p ⱕ 0.05 level are reported.
Results Demographic characteristics of the 1197 respondents are presented in Table 1. The percentage of respondents not providing answers to any given question regarding demographic or clinical information was low (ⱕ2%). Only one participant did not respond to the question regarding glaucoma awareness. Overall, 28% of respondents claimed to be unfamiliar with glaucoma (being unaware of glaucoma was defined as a negative response to question 14 on the questionnaire) compared with 20% of the subgroup reporting a diagnosis of glaucoma (Table 2). Crude associations between demographic and clinical fators and glaucoma awareness, based on chi-squared statistics, appear in Table 2. There was no crude association between gender, diabetes, cardiovascular disease, or steroid use and glaucoma awareness. Therefore, data pertaining to the association of these attributes and glaucoma awareness were omitted. Adjusted odds ratios for demographic and clinical variables that were associated with being unaware of glaucoma in a multivariate logistic regression model appear in Table 3. Respondents
Table 1. Self-reported Characteristics of Questionnaire Respondents (n ⫽ 1197) N* Age (yrs): Mean ⫾ SD: 54 ⫾ 19 (range: 16–95) ⱕ19 20–34 35–49 50–64 65–79 ⱖ80 Gender: Male Race/ethnicity Caucasian African American Hispanic Asian Other Education: ⬍ High school degree High school degree 2–4 yrs college Master’s or doctorate degree History of employment in the health field Diabetes Systemic hypertension Cardiovascular disease Myopia Glaucoma Steroid use History of glaucoma in first-degree relative History of dilated eye examination
Percent†
No. Missing‡ 1
29 210 273 264 335 85 497
2 18 23 22 28 7 42
890 159 72 52 9
74 13 6 3 1
164 314 490 205
14 26 41 17
237 110 318 143 452 71 100
20 9 27 12 38 6 8
4 2 1 1 1 2 2
244 949
20 79
9 18
1 15
24
*Number of respondents with the characteristic. †Frequency of the characteristic. ‡Number of surveys with information missing.
aged 50 to 79 years were less likely to be unaware of glaucoma than those younger than 35. Age older than 79 years was not an independent predictor of glaucoma awareness. Hispanic ethnicity was the strongest independent determinant of being unaware of glaucoma. Respondents of African American heritage and those with less than a college education were roughly 65% more likely to be unaware of glaucoma. Respondents who claimed to have a dilated eye examination were least likely to be unfamiliar with glaucoma. Respondents reporting history of employment in the health field, myopia, or glaucoma in a first-degree relative were also less likely to be unfamiliar with glaucoma than those who did not have these attributes. Systemic hypertension, which was a predictor of glaucoma awareness in the crude analysis (Table 2), was not an independent determinant of glaucoma awareness in multivariate analysis. Similarly, having a diagnosis of glaucoma was not an independent predictor of glaucoma awareness, although there was a trend toward enhanced glaucoma awareness in this subgroup. The use of age as a continuous variable, rather than a categorical variable, did not significantly alter the results of the multivariate model presented in Table 3 (data not shown). Repeating the logistic regression model, excluding respondents who did report having glaucoma, did not alter the results (data not shown).
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Ophthalmology Volume 107, Number 2, Feburary 2000 Table 2. Glaucoma Awareness as a Function of Respondent Attributes Frequency (%) of Glaucoma Awareness (%) p Value*
Attribute Age (yrs) ⱕ19 20–34 35–49 50–64 65–79 ⱖ80 Race/ethnicity Caucasian African American Hispanic Asian Education ⬍High school degree High school degree 2–4 yrs college Master’s or doctorate degree History of employment in the health field Systemic hypertension Myopia Glaucoma History of glaucoma in first-degree relative History of dilated eye examination
18/29 (62) 133/210 (63) 186/273 (68) 200/264 (76) 255/335 (76) 55/85 (65)
0.294 0.009 0.266 0.046 0.012 0.198
667/890 (75) 98/159 (62) 34/72 (47) 32/52 (62)
0.001 0.006 0.001 0.132
80/164 (49) 224/314 (71) 364/490 (74) 165/205 (80)
0.001 0.814 0.028 0.001
184/237 (78) 240/318 (75) 351/452 (78) 57/71 (80)
0.010 0.033 0.001 0.071
192/244 (79) 712/949 (75)
0.002 0.001
*p value is for chi-square statistic comparing percentage aware of glaucoma with attribute versus percentage aware of glaucoma without attribute.
Discussion Glaucoma is an insidious disease with no symptoms until the condition is advanced. Effective education about the disease could diminish its personal and federal burden by
influencing individuals to undergo appropriate screening leading to early detection and treatment. Because resources are not limitless, one strategy for an efficient public health education program would involve targeting subgroups who are at risk for both developing glaucoma and being unfamiliar with the disease. African American race is a wellestablished risk factor for primary open-angle glaucoma,3 and this group comprises a disproportionately high percentage of patients in US glaucoma blindness registries.1 Our study indicates that African American race also is a risk factor for being unfamiliar with glaucoma. Hispanic ethnicity was another attribute associated with reduced glaucoma awareness. The prevalence of glaucoma in Hispanics has not been studied extensively. However, one study indicates a particularly high prevalence of pseudoexfoliation syndrome among one subgroup: Hispanic American males in New Mexico are 5.8 times more likely to develop pseudoexfoliation than non-Hispanic controls, and those with pseudoexfoliation are 22 times more likely to develop glaucoma than age-matched controls.13 Furthermore, Hispanics have a higher risk of diabetes than white or non-Hispanic black adults,14 and Mexican Americans with diabetes have a higher prevalence of glaucoma than those without the disease.15 Thus some subgroups of Hispanics may be at increased risk for glaucoma, including one subgroup—Mexican Americans—that is the second largest and most rapidly increasing ethnic population in the United States.16 These findings and our data suggest enhanced need for glaucoma education among at least some subgroups of Hispanics. Because a language barrier cannot be ruled out as a cause of reduced glaucoma awareness among Hispanics, a public health strategy using a bilingual approach is prudent. In the Baltimore Eye Survey, the number of school years completed was inversely associated with the prevalence of blindness and visual impairment from all causes, including
Table 3. Attributes Associated With Being Unaware of Glaucoma in a Multivariate Logistic Regression Model Attribute Age (yrs) ⬍35 35–49 50–64 65–79 ⱖ80 Male gender Race/ethnicity Caucasian/Asian/other African American Hispanic Education ⬍College ⱖ2 yrs college History of employment in the health field Systemic hypertension Myopia Glaucoma History of glaucoma in first-degree relative History of dilated eye examination *CI ⫽ confidence interval.
306
Adjusted Odds Ratio
95% CI*
p Value
1.0 0.85 0.60 0.56 0.85 0.85
— 0.58–1.26 0.44–0.80 0.41–0.75 0.47–1.54 0.64–1.12
— 0.41 0.02 0.0067 0.58 0.26
1.0 1.69 2.13
— 1.28–2.20 1.46–3.02
— 0.0057 0.0044
1.67 1.0 0.63 0.79 0.68 0.63 0.68 0.53
1.37–2.05 — 0.49–0.82 0.56–1.09 0.56–0.82 0.33–1.17 0.53–0.87 0.42–0.66
0.0004 — 0.013 0.16 0.0094 0.16 0.036 0.0001
Gasch et al. 䡠 Determinants of Glaucoma Awareness glaucoma. This association was significant even after adjusting for potential confounding variables, including race and age.17 This is consistent with our study’s finding that less formally educated individuals, particularly those with less than a college education, are unlikely to be familiar with glaucoma and thus constitute a potentially rewarding target for glaucoma education. Education level probably is tied to socioeconomic status that, in turn, may be linked to ability to access the health care system. Thus many patients unaware of glaucoma may not have access to the health care system. Therefore, our study suggests that in addition to physician-directed efforts to enhance glaucoma awareness, such as Celebrate Sight (Glaucoma 2001), more comprehensive programs may be required to reduce the burden of glaucoma blindness in the United States. Strong evidence exists that public health education can be effective in reducing morbidity: Since implementation of the National High Blood Pressure Education Program, there has been a progressive decline in age-adjusted mortality rates for stroke.18 In addition, implementation of the National Cholesterol Education Program has been associated both with declining dietary intakes of saturated fat, total fat, and cholesterol and with falling serum cholesterol levels.19 Both programs have been associated with a progressive decline in age-adjusted mortality rates for coronary heart disease.18,19 These precedents suggest that public education could reduce vision loss from glaucoma. Overall glaucoma awareness in this clinic-based population was high, raising two fundamental questions. First, do our results apply to the general population because the latter group contains people who do not seek eye care? Interestingly, a population-based study of eye care use among older Americans concludes that African-Americans and those with less than a high school education were less likely to see an eye care professional (eye care use by Hispanics was not discussed).20 In our study these attributes also were risk factors for being unfamiliar with glaucoma. Thus although the crude rate of glaucoma awareness may vary from study to study, the attributes associated with being unfamiliar with glaucoma are likely to be duplicated in a population-based sample. Second, are there any extenuating circumstances that explain the relatively high prevalence of glaucoma awareness in our sample? There are no glaucoma education materials or programs currently available in the clinic where we recruited participants. There are five teaching hospitals that employ 20% of the population living in Boston.21 Similarly, 20% of our sample reported a history of employment in the health field (Table 1). This attribute also was found to be an independent predictor of being aware of glaucoma (Table 3). This demographic feature may account for the overall high level of glaucoma awareness we noted, but it in no way detracts from our major findings. The level of glaucoma awareness in our sample as a whole (72%) approached that of study participants claiming to have glaucoma (80%). The latter awareness level (80%) may approximate the upper bound of any glaucoma education program. Alternatively, the level of glaucoma awareness we found among glaucoma patients, which was substantially less than 100%, could reflect inadequate education about the disease rather than the upper bound of glaucoma
awareness achievable by a well-designed glaucoma education program. Two previous studies also reported that 6%9 and 26%22 of patients under treatment for glaucoma did not know they had the disease. These findings indicate that more physician-directed patient education is needed to enhance glaucoma awareness in the clinical setting. Not only does knowledge about glaucoma improve compliance of patients with the disease,23 but it also might increase the likelihood that glaucoma patients would prompt relatives to undergo glaucoma screening. Both short videos24,25 and brochures25 have proven to be effective means of educating glaucoma patients about their disease, although knowledge obtained by video needs reinforcement because it decays over time.24,25 In addition, videos and brochures are simple, economical, and time-saving methods of education. However, personal contact has greater impact.26 Similar to our study, previous studies found lack of family history of glaucoma8,9,11 to be associated with poor knowledge about glaucoma. Also like our study, one study found no association between gender and glaucoma knowledge,11 although two other studies found male gender to be associated with poor knowledge about the disease.8,10 Apparently, no prior study analyzed the relationship between employment in the health field or refractive status and glaucoma awareness. Intuitively, it is not surprising that we found glaucoma awareness to be positively associated with employment in the health field. The positive association between myopia and glaucoma awareness may result because myopes have more contact with eye-care providers because of the need for eyeglasses and thus have more glaucoma checks and more potential for exposure to information about glaucoma than hyperopes, who may see adequately with over-the-counter eyeglasses, or emmetropes. A similar explanation may be invoked to explain why respondents who had dilated eye examinations had heightened glaucoma awareness. No eyeglasses and/or contact lens use11 (Pfeiffer N, Krieglstein GK. Invest Ophthalmol Vis Sci 1193); 34 [Suppl]: 1192 and not having been tested for glaucoma8 have been associated with poor knowledge about glaucoma. Our questionnaire was not designed to examine depth or accuracy of knowledge about glaucoma. Thus respondents who indicated that they were familiar with glaucoma could have had only superficial and/or inaccurate awareness of the disease, and those who indicated the converse could have had some knowledge of the disease but considered the extent inadequate for an affirmative response to question 14. However, evidence exists that individuals who feel inadequately informed about glaucoma exhibit significantly less knowledge about the disease than those who feel the opposite.25 In addition, our questionnaire may not have assessed some important attributes, which may confound the relationships observed in our study. For example, the relation between socioeconomic status and glaucoma awareness was not explored, although our multivariate analysis did adjust for education level. Public education focusing on increasing disease awareness is crucial in combating vision loss from glaucoma. Our study indicates that Hispanics, African Americans, and individuals with less than a college education may warrant targeting by public health education initiatives to improve
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Ophthalmology Volume 107, Number 2, Feburary 2000 knowledge about glaucoma. Further population-based study is needed to determine whether the findings are more widely applicable. More specific determination of knowledge about glaucoma in future studies would be useful to unveil misconceptions that need addressing. It is notable that a survey itself can be educational by prompting respondents to obtain information about the survey topic.8
References 1. Sommer A, Tielsch JM, Katz J, et al. Racial differences in the cause-specific prevalence of blindness in East Baltimore. N Engl J Med 1991;325:1412–7. 2. Quigley HA, Vitale S. Models of open-angle glaucoma prevalence and incidence in the United States. Invest Ophthalmol Vis Sci 1997;38:83–91. 3. Tielsch JM, Sommer A, Katz J, et al. Racial variations in the prevalence of primary open-angle glaucoma. The Baltimore Eye Survey. JAMA 1991;266:369 –74. 4. Parrish RK II, Gedde SJ, Scott IU, et al. Visual function and quality of life among patients with glaucoma. Arch Ophthalmol 1997;115:1447–55. 5. Gutierrez P, Wilson MR, Johnson C, et al. Influence of glaucomatous visual field loss on health-related quality of life. Arch Ophthalmol 1997;115:777– 84. 6. Sherwood MB, Garcia-Siekavizza A, Meltzer MI, et al. Glaucoma’s impact on quality of life and its relation to clinical indicators: a pilot study. Ophthalmology 1998;105:561– 6. 7. Javitt JC. Preventing blindness in Americans: the need for eye health education. Surv Ophthalmol 1995;40:41– 4. 8. Michielutte R, Diseker RA, Stafford CL, Carr P. Knowledge of diabetes and glaucoma in a rural North Carolina community. J Community Health 1984;9:269 – 84. 9. Elliott AJ. Glaucoma: ignorance and apathy [letter]. Eye 1989; 3:485– 6. 10. Livingston PM, Lee SE, De Paola C, et al. Knowledge of glaucoma, and its relationship to self-care practices, in a population sample. Aust N Z J Ophthalmol 1995;23:37– 41. 11. Attebo K, Mitchell P, Cumming R, Smith W. Knowledge and beliefs about common eye diseases. Aust N Z J Ophthalmol 1997;25:283–7.
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12. Yen MT, Wu CY, Higginbotham EJ. Importance of increasing public awareness regarding glaucoma [letter]. Arch Ophthalmol 1996;114:635. 13. Jones W, White RE, Magnus DE. Increased occurrence of exfoliation in the male, Spanish American population of New Mexico. J Am Optom Assoc 1992;63:643– 8. 14. Perez-Stable EJ, McMillen MM, Harris MI, et al. Self-reported diabetes in Mexican Americans: HHANES 1982– 84. Am J Public Health 1989;79:770 –2. 15. Zhang J, Markides KS, Lee DJ. Health status of diabetic Mexican Americans: results from the Hispanic HANES. Ethn Dis 1991;1:273–9. 16. Raymond CA. Diabetes in Mexican-Americans: pressing problem in a growing population. JAMA 1988;259:1772. 17. Tielsch JM, Sommer A, Katz J, et al. Socioeconomic status and visual impairment among urban Americans. Arch Ophthalmol 1991;109:637– 41. 18. The sixth report of the Joint National Committee on prevention, detection, evaluation, and treatment of high blood pressure. Arch Intern Med 1997;157:2413– 46. 19. Cleeman JI, Lenfant C. The National Cholesterol Education Program: progress and prospects. JAMA 1998;280:2099 –104. 20. Orr P, Barron Y, Schien OD, et al. Eye care utilization by older Americans: the SEE Project. Salisbury Eye Evaluation. Ophthalmology 1999;106:904 –9. 21. Pham A. Teaching hospitals in Boston. The Boston Globe 1999;255:78,A12. 22. MacKean JM, Elkington AR. Alerting close relatives of patients with glaucoma [letter]. BMJ (Clin Res Ed) 1984;289: 800 –1. 23. Zimmerman TJ, Zalta AH. Facilitating patient compliance in glaucoma therapy. Surv Ophthalmol 1983;28(Suppl): 252– 8. 24. Rosenthal AR, Zimmerman JF, Tanner J. Educating the glaucoma patient. Br J Ophthalmol 1983;67:814 –7. 25. Kim S, Stewart JF, Emond MJ, et al. The effect of a brief education program on glaucoma patients. J Glaucoma 1997; 6:146 –51. 26. Cook TD. Major research analysis provides proof: patient education does make a difference. Promot Health 1984;5:4 – 5,9.
Originally received: May 3, 1999. Accepted: September 29, 1999. Manuscript no. 99213. 1 Massachusetts Eye and Ear Infirmary, Boston, Massachusetts. 2 Division of Pharmacoepidemiology and Pharmacoeconomics, Brigham and Women’s Hospital, Boston, Massachusetts. 3 Division of Ophthalmology, Brigham and Women’s Hospital, Boston, Massachusetts. Presented at the annual meeting of ARVO, Ft. Lauderdale, Florida, May, 1999. No financial support was received for this study. The authors have no proprietary or financial interest in any products used in this study. Reprint requests to Louis R. Pasquale, MD, Glaucoma Consultation Service, Massachusetts Eye and Ear Infirmary, 243 Charles St, Boston, MA 02114. © 2000 by the American Academy of Ophthalmology Published by Elsevier Science Inc.
only about half of them are aware that they have the disease.3 Visual loss resulting from glaucomatous optic neuropathy has a negative impact on a variety of visually oriented tasks necessary to function independently in society.4 – 6 This is of special concern because of the present trend toward dissolution of the nuclear family. Eye health education that influences individuals to participate in regular ophthalmologic care may be an important means of detecting glaucoma early, thereby preventing needless visual impairment and preserving quality of life.7 Celebrate Sight (formerly known as Glaucoma 2001) represents one strategy to increase glaucoma awareness by educating primary caregivers and the public about the disease. To most efficiently use resources to enhance public awareness about glaucoma, subgroups of the population that are at highest risk for both developing the disease and having insufficient knowledge about it need to be identified and targeted. Several studies have examined knowledge and/or beliefs about glaucoma in general clinic or population-based samples,8 –12 (Pfeiffer N, Krieglstein GK. Invest Ophthalmol Vis Sci 1993); 34 [Suppl]: 1192, but there never has been a ISSN 0161-6420/00/$–see front matter PII S0161-6420(99)00076-7
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Ophthalmology Volume 107, Number 2, Feburary 2000
Figure 1. Questionnaire.
comparable large-scale analysis conducted in a US urban center. Previous surveys conducted in a US rural center, England, Australia, and Germany indicate that 7% to 70% of participants report they are unfamiliar with glaucoma.8 –11 (Pfeiffer N, Krieglstein GK. Invest Opthalmol Vis Sci 1993); 34 [Suppl]: 1192. Analysis of these data indicates that age,8 family history of glaucoma,11 and education8,10,11 are determinants of glaucoma awareness. To the best of our knowledge, no prior study of glaucoma awareness evaluated race or ethnicity as a predictor of glaucoma awareness. Therefore, we assessed the relation between various demographic and clinical features and glaucoma awareness in a large, urban general eye clinic.
304
Materials and Methods A questionnaire (Fig. 1) was randomly distributed during a 4-month period in 1998 to nonconsecutive patients and their companions at the General Eye Service at the Massachusetts Eye and Ear Infirmary. No individuals were excluded from participation in the study on the basis of age. Those unable to write or communicate in English were excluded from the study. Less than 2% of individuals approached to participate in the study declined to do so. Respondents were not prompted to possible responses. No distributed questionnaire was excluded from analysis. No patient identifiers were maintained after the survey was completed. The Human Studies Committee of the Massachusetts Eye and Ear Infirmary approved the study. We calculated the sample size on the
Gasch et al. 䡠 Determinants of Glaucoma Awareness basis of having an 80% chance of identifying an attribute associated with glaucoma awareness, assuming that the attribute was present in 5% of the sample. In estimating our sample size, we aimed to detect a 15% difference in study attributes when the sample was stratified by glaucoma awareness. Other assumptions in our sample size calculation include a type I error of 0.05 and a 20% variance in survey attributes in the sample. The questionnaire was designed to capture information about demographics, risk factors for primary open-angle glaucoma, and awareness of glaucoma. It was designed to be brief, with most questions requiring “yes” or “no” answers. Questions related to family history of glaucoma also provided the option of “don’t know” as a response. Questions related to family history of glaucoma purposely were repeated for parents, siblings, and other relatives to enhance recall of a possible positive response. The questions were modified slightly after pilot administration to lay staff at the Massachusetts Eye and Ear Infirmary. Because there is consensus among previous studies that less educated individuals are more likely to be unaware of glaucoma,8,10,11 we used this question to validate our assessment of glaucoma awareness. Univariate analysis of the first 10% and first 30% of surveys showed a strong positive association between education and glaucoma awareness (data not shown). In performing statistical analysis of the overall data, we initially examined the proportion of subjects claiming awareness of glaucoma within the entire study population and within strata defined by demographic and clinical features. We also assessed the proportion of subjects in the entire study population and within strata, who endorsed other survey questions. Crude relationships between demographic or clinical variables and glaucoma awareness were explored with chi-square statistics. To examine the independent effects of demographic and clinical variables on the likelihood of being unaware of glaucoma, we constructed several multivariate logistic regression models. Age, gender, and race were included in the models as categorical variables. Age also was used as a continuous variable in modeling the data. Remaining demographic and clinical variables then were subjected to a forward stepwise selection procedure in which variables significantly associated with the outcome at the p ⱕ 0.2 level were included. Adjusted odds ratios and the associated 95% confidence intervals for attributes that are independent predictors of glaucoma awareness at the p ⱕ 0.05 level are reported.
Results Demographic characteristics of the 1197 respondents are presented in Table 1. The percentage of respondents not providing answers to any given question regarding demographic or clinical information was low (ⱕ2%). Only one participant did not respond to the question regarding glaucoma awareness. Overall, 28% of respondents claimed to be unfamiliar with glaucoma (being unaware of glaucoma was defined as a negative response to question 14 on the questionnaire) compared with 20% of the subgroup reporting a diagnosis of glaucoma (Table 2). Crude associations between demographic and clinical fators and glaucoma awareness, based on chi-squared statistics, appear in Table 2. There was no crude association between gender, diabetes, cardiovascular disease, or steroid use and glaucoma awareness. Therefore, data pertaining to the association of these attributes and glaucoma awareness were omitted. Adjusted odds ratios for demographic and clinical variables that were associated with being unaware of glaucoma in a multivariate logistic regression model appear in Table 3. Respondents
Table 1. Self-reported Characteristics of Questionnaire Respondents (n ⫽ 1197) N* Age (yrs): Mean ⫾ SD: 54 ⫾ 19 (range: 16–95) ⱕ19 20–34 35–49 50–64 65–79 ⱖ80 Gender: Male Race/ethnicity Caucasian African American Hispanic Asian Other Education: ⬍ High school degree High school degree 2–4 yrs college Master’s or doctorate degree History of employment in the health field Diabetes Systemic hypertension Cardiovascular disease Myopia Glaucoma Steroid use History of glaucoma in first-degree relative History of dilated eye examination
Percent†
No. Missing‡ 1
29 210 273 264 335 85 497
2 18 23 22 28 7 42
890 159 72 52 9
74 13 6 3 1
164 314 490 205
14 26 41 17
237 110 318 143 452 71 100
20 9 27 12 38 6 8
4 2 1 1 1 2 2
244 949
20 79
9 18
1 15
24
*Number of respondents with the characteristic. †Frequency of the characteristic. ‡Number of surveys with information missing.
aged 50 to 79 years were less likely to be unaware of glaucoma than those younger than 35. Age older than 79 years was not an independent predictor of glaucoma awareness. Hispanic ethnicity was the strongest independent determinant of being unaware of glaucoma. Respondents of African American heritage and those with less than a college education were roughly 65% more likely to be unaware of glaucoma. Respondents who claimed to have a dilated eye examination were least likely to be unfamiliar with glaucoma. Respondents reporting history of employment in the health field, myopia, or glaucoma in a first-degree relative were also less likely to be unfamiliar with glaucoma than those who did not have these attributes. Systemic hypertension, which was a predictor of glaucoma awareness in the crude analysis (Table 2), was not an independent determinant of glaucoma awareness in multivariate analysis. Similarly, having a diagnosis of glaucoma was not an independent predictor of glaucoma awareness, although there was a trend toward enhanced glaucoma awareness in this subgroup. The use of age as a continuous variable, rather than a categorical variable, did not significantly alter the results of the multivariate model presented in Table 3 (data not shown). Repeating the logistic regression model, excluding respondents who did report having glaucoma, did not alter the results (data not shown).
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Ophthalmology Volume 107, Number 2, Feburary 2000 Table 2. Glaucoma Awareness as a Function of Respondent Attributes Frequency (%) of Glaucoma Awareness (%) p Value*
Attribute Age (yrs) ⱕ19 20–34 35–49 50–64 65–79 ⱖ80 Race/ethnicity Caucasian African American Hispanic Asian Education ⬍High school degree High school degree 2–4 yrs college Master’s or doctorate degree History of employment in the health field Systemic hypertension Myopia Glaucoma History of glaucoma in first-degree relative History of dilated eye examination
18/29 (62) 133/210 (63) 186/273 (68) 200/264 (76) 255/335 (76) 55/85 (65)
0.294 0.009 0.266 0.046 0.012 0.198
667/890 (75) 98/159 (62) 34/72 (47) 32/52 (62)
0.001 0.006 0.001 0.132
80/164 (49) 224/314 (71) 364/490 (74) 165/205 (80)
0.001 0.814 0.028 0.001
184/237 (78) 240/318 (75) 351/452 (78) 57/71 (80)
0.010 0.033 0.001 0.071
192/244 (79) 712/949 (75)
0.002 0.001
*p value is for chi-square statistic comparing percentage aware of glaucoma with attribute versus percentage aware of glaucoma without attribute.
Discussion Glaucoma is an insidious disease with no symptoms until the condition is advanced. Effective education about the disease could diminish its personal and federal burden by
influencing individuals to undergo appropriate screening leading to early detection and treatment. Because resources are not limitless, one strategy for an efficient public health education program would involve targeting subgroups who are at risk for both developing glaucoma and being unfamiliar with the disease. African American race is a wellestablished risk factor for primary open-angle glaucoma,3 and this group comprises a disproportionately high percentage of patients in US glaucoma blindness registries.1 Our study indicates that African American race also is a risk factor for being unfamiliar with glaucoma. Hispanic ethnicity was another attribute associated with reduced glaucoma awareness. The prevalence of glaucoma in Hispanics has not been studied extensively. However, one study indicates a particularly high prevalence of pseudoexfoliation syndrome among one subgroup: Hispanic American males in New Mexico are 5.8 times more likely to develop pseudoexfoliation than non-Hispanic controls, and those with pseudoexfoliation are 22 times more likely to develop glaucoma than age-matched controls.13 Furthermore, Hispanics have a higher risk of diabetes than white or non-Hispanic black adults,14 and Mexican Americans with diabetes have a higher prevalence of glaucoma than those without the disease.15 Thus some subgroups of Hispanics may be at increased risk for glaucoma, including one subgroup—Mexican Americans—that is the second largest and most rapidly increasing ethnic population in the United States.16 These findings and our data suggest enhanced need for glaucoma education among at least some subgroups of Hispanics. Because a language barrier cannot be ruled out as a cause of reduced glaucoma awareness among Hispanics, a public health strategy using a bilingual approach is prudent. In the Baltimore Eye Survey, the number of school years completed was inversely associated with the prevalence of blindness and visual impairment from all causes, including
Table 3. Attributes Associated With Being Unaware of Glaucoma in a Multivariate Logistic Regression Model Attribute Age (yrs) ⬍35 35–49 50–64 65–79 ⱖ80 Male gender Race/ethnicity Caucasian/Asian/other African American Hispanic Education ⬍College ⱖ2 yrs college History of employment in the health field Systemic hypertension Myopia Glaucoma History of glaucoma in first-degree relative History of dilated eye examination *CI ⫽ confidence interval.
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Adjusted Odds Ratio
95% CI*
p Value
1.0 0.85 0.60 0.56 0.85 0.85
— 0.58–1.26 0.44–0.80 0.41–0.75 0.47–1.54 0.64–1.12
— 0.41 0.02 0.0067 0.58 0.26
1.0 1.69 2.13
— 1.28–2.20 1.46–3.02
— 0.0057 0.0044
1.67 1.0 0.63 0.79 0.68 0.63 0.68 0.53
1.37–2.05 — 0.49–0.82 0.56–1.09 0.56–0.82 0.33–1.17 0.53–0.87 0.42–0.66
0.0004 — 0.013 0.16 0.0094 0.16 0.036 0.0001
Gasch et al. 䡠 Determinants of Glaucoma Awareness glaucoma. This association was significant even after adjusting for potential confounding variables, including race and age.17 This is consistent with our study’s finding that less formally educated individuals, particularly those with less than a college education, are unlikely to be familiar with glaucoma and thus constitute a potentially rewarding target for glaucoma education. Education level probably is tied to socioeconomic status that, in turn, may be linked to ability to access the health care system. Thus many patients unaware of glaucoma may not have access to the health care system. Therefore, our study suggests that in addition to physician-directed efforts to enhance glaucoma awareness, such as Celebrate Sight (Glaucoma 2001), more comprehensive programs may be required to reduce the burden of glaucoma blindness in the United States. Strong evidence exists that public health education can be effective in reducing morbidity: Since implementation of the National High Blood Pressure Education Program, there has been a progressive decline in age-adjusted mortality rates for stroke.18 In addition, implementation of the National Cholesterol Education Program has been associated both with declining dietary intakes of saturated fat, total fat, and cholesterol and with falling serum cholesterol levels.19 Both programs have been associated with a progressive decline in age-adjusted mortality rates for coronary heart disease.18,19 These precedents suggest that public education could reduce vision loss from glaucoma. Overall glaucoma awareness in this clinic-based population was high, raising two fundamental questions. First, do our results apply to the general population because the latter group contains people who do not seek eye care? Interestingly, a population-based study of eye care use among older Americans concludes that African-Americans and those with less than a high school education were less likely to see an eye care professional (eye care use by Hispanics was not discussed).20 In our study these attributes also were risk factors for being unfamiliar with glaucoma. Thus although the crude rate of glaucoma awareness may vary from study to study, the attributes associated with being unfamiliar with glaucoma are likely to be duplicated in a population-based sample. Second, are there any extenuating circumstances that explain the relatively high prevalence of glaucoma awareness in our sample? There are no glaucoma education materials or programs currently available in the clinic where we recruited participants. There are five teaching hospitals that employ 20% of the population living in Boston.21 Similarly, 20% of our sample reported a history of employment in the health field (Table 1). This attribute also was found to be an independent predictor of being aware of glaucoma (Table 3). This demographic feature may account for the overall high level of glaucoma awareness we noted, but it in no way detracts from our major findings. The level of glaucoma awareness in our sample as a whole (72%) approached that of study participants claiming to have glaucoma (80%). The latter awareness level (80%) may approximate the upper bound of any glaucoma education program. Alternatively, the level of glaucoma awareness we found among glaucoma patients, which was substantially less than 100%, could reflect inadequate education about the disease rather than the upper bound of glaucoma
awareness achievable by a well-designed glaucoma education program. Two previous studies also reported that 6%9 and 26%22 of patients under treatment for glaucoma did not know they had the disease. These findings indicate that more physician-directed patient education is needed to enhance glaucoma awareness in the clinical setting. Not only does knowledge about glaucoma improve compliance of patients with the disease,23 but it also might increase the likelihood that glaucoma patients would prompt relatives to undergo glaucoma screening. Both short videos24,25 and brochures25 have proven to be effective means of educating glaucoma patients about their disease, although knowledge obtained by video needs reinforcement because it decays over time.24,25 In addition, videos and brochures are simple, economical, and time-saving methods of education. However, personal contact has greater impact.26 Similar to our study, previous studies found lack of family history of glaucoma8,9,11 to be associated with poor knowledge about glaucoma. Also like our study, one study found no association between gender and glaucoma knowledge,11 although two other studies found male gender to be associated with poor knowledge about the disease.8,10 Apparently, no prior study analyzed the relationship between employment in the health field or refractive status and glaucoma awareness. Intuitively, it is not surprising that we found glaucoma awareness to be positively associated with employment in the health field. The positive association between myopia and glaucoma awareness may result because myopes have more contact with eye-care providers because of the need for eyeglasses and thus have more glaucoma checks and more potential for exposure to information about glaucoma than hyperopes, who may see adequately with over-the-counter eyeglasses, or emmetropes. A similar explanation may be invoked to explain why respondents who had dilated eye examinations had heightened glaucoma awareness. No eyeglasses and/or contact lens use11 (Pfeiffer N, Krieglstein GK. Invest Ophthalmol Vis Sci 1193); 34 [Suppl]: 1192 and not having been tested for glaucoma8 have been associated with poor knowledge about glaucoma. Our questionnaire was not designed to examine depth or accuracy of knowledge about glaucoma. Thus respondents who indicated that they were familiar with glaucoma could have had only superficial and/or inaccurate awareness of the disease, and those who indicated the converse could have had some knowledge of the disease but considered the extent inadequate for an affirmative response to question 14. However, evidence exists that individuals who feel inadequately informed about glaucoma exhibit significantly less knowledge about the disease than those who feel the opposite.25 In addition, our questionnaire may not have assessed some important attributes, which may confound the relationships observed in our study. For example, the relation between socioeconomic status and glaucoma awareness was not explored, although our multivariate analysis did adjust for education level. Public education focusing on increasing disease awareness is crucial in combating vision loss from glaucoma. Our study indicates that Hispanics, African Americans, and individuals with less than a college education may warrant targeting by public health education initiatives to improve
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Ophthalmology Volume 107, Number 2, Feburary 2000 knowledge about glaucoma. Further population-based study is needed to determine whether the findings are more widely applicable. More specific determination of knowledge about glaucoma in future studies would be useful to unveil misconceptions that need addressing. It is notable that a survey itself can be educational by prompting respondents to obtain information about the survey topic.8
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