Rural Chinese Population Research Articles

Eye Care Use Among Rural Adults in China: The Handan Eye Study

Purpose: To assess the use of eye care services in a rural population in North China and to analyze the factors associated with underuse of these services.Methods: In a cross-sectional population-based study, demographic, health and vision-related information including use of eye care services were determined during a face-to-face interview. A single visit to an eye care provider qualified as “use” of eye care services.Results: Of 6612 participants, 754 (11.4%, 95% confidence interval, CI, 8.7–14.1%) had used eye care services. The most common reason cited for not seeing an eye care provider was “no need” (n = 5754). Of the 5754 who thought that there was no need to see an ophthalmologist, 3458 (60.1%) were found to have one or more type of eye disease, including glaucoma (56, 1.0%), cataract (1056, 18.4%), age-related macular degeneration (AMD; 164, 2.9%) and refractive error (3048, 53.0%). Also, 74 (1.3%) and 409 (7.1%) of the 5754 participants had visual impairment (<20/60) according to best-corrected visual acuity and presenting visual acuity, respectively. In a multiple regression model, participants who had glaucoma (adjusted odds ratio, OR, 4.0, 95% CI 3.0–5.4), AMD (adjusted OR 1.6, 95% CI 1.2–2.3) or refractive error (adjusted OR 1.4, 95% CI 1.1–1.8), were more likely to visit an eye care provider.Conclusion: A high proportion of the Chinese rural population had never used eye care services although three fifths had eye diseases. Further efforts towards better education of the general population about common eye problems as well as increasing the number of ocular health providers would be necessary in future.

Prevalence and risk factors of posterior vitreous detachment in a Chinese adult population: the Handan eye study

BackgroundTo describe the prevalence and associations of posterior vitreous detachment (PVD) in a rural adult Chinese population.MethodsAll eligible subjects were requested to carry out a comprehensive eye examination; PVD was a pre-specified outcome variable and was determined via biomicroscopical examination (slit-lamp biomicroscopy) with a +90-D preset lens after mydriasis. Prevalence was standardized to China population census (2000).Results5890 (86.2%) subjects completed the examination of slit-lamp biomicroscopy with a +90-D lens. PVD was present in 160 participants (2.7%); the standardized prevalence was 2.0% (95% confidence interval [CI], 1.6-2.3%). PVD developed increasingly with age (P for trend < 0.001) for both men and women. Using a multivariate regression model, older people were found to run a higher risk of developing PVD than younger people, and women were found to have a higher risk than men (OR, 2.9; 95% CI, 1.5-5.9). Diabetes, hypertension, smoking, drinking, and intraocular pressure (IOP) were not significantly associated with PVD.ConclusionsAbout one in fifty people is found to have PVD in this population-based study. Age and female are independently associated with PVD occurrence.

Association between dietary protein intake and the risk of hypertension: a cross-sectional study from rural western China

Evidence for an association between dietary proteins and the risk of hypertension in rural Chinese adults, whose diets are protein-poor and unbalanced, is limited. The aim of this study was to investigate the effect of dietary proteins on hypertension among adults of rural western China. A cross-sectional survey was conducted in Hanzhong, China, and 2241 residents were included in the analysis. Logistic regression models were used to examine whether dietary proteins (total, plant and animal protein) were independently correlated with hypertension. The total protein intake was inadequate (51.7 g per day for male and 40.1 g per day for female), accounting for 56-71% of the Chinese recommended nutrient intakes or adequate intakes. Nearly 80% of protein intake derived from plants, especially grains, and the proportion derived from plants was higher in females than in males. The daily animal protein intake was 12.1 g for males and 8.3 g for females. For females, no significant association was found between hypertension and total protein or plant protein intake. However, animal protein intake was significantly and negatively associated with the risk of hypertension after controlling for demographic characteristics, lifestyle factors, body mass index and other dietary nutrients. In addition, the odds ratio for the upper quartile compared with the bottom quartile was 0.64 (95% confidence interval, CI: 0.43-0.95, P for trend <0.05). Furthermore, a significant decrease of 1.082 mm Hg (95%CI: 0.189-1.975) in systolic blood pressure and 0.668 mm Hg (95%CI: 0.105-1.232) in diastolic blood pressure was observed per s.d. increase of animal protein intake in females. For males, we did not observe a significant association between dietary proteins and hypertension or blood pressure. In conclusion, for the western rural Chinese population, especially women, whose dietary protein intake is low and largely derived from plants, the intake of animal protein may be related to a decreased risk of hypertension.

Psychological strains and depression in Chinese rural populations

Objective: The aim of this study is to explore the relationship between psychological strains and depression and to further test the Strain Theory of Suicide and Mental Disorders. Method: Data for the current study were from a large psychological autopsy (PA) study in Chinese rural populations with a case-control design to investigate the environmental and other characteristics of rural young suicides and controls. Subjects (N = 1618) for the current study were the informants in the PA interviews. The center for epidemiologic studies depression scale was used to assess the respondents’ depression level. Chi-square , t test, t′ test, and general linear regression model were used to analyse the data by SPSS software. Results: Value strain and deprivation strain are positively correlated with the depression level for both men and women of the Chinese rural population. Religion is another strong risk factor for depression and marriage is not a protective factor for depression in this sample. Conclusions: The study verifies that there is strong correlation between the psychological strains and depression in Chinese rural populations. It is suggested that reducing psychological strains may be a possible approach to reduce the prevalence of depression so as to help bring down the suicide risk in rural China.

Metabolic syndrome, C-reactive protein and microalbuminuria in a rural Chinese population: a cross-sectional study

BackgroundMicroalbuminuria is an early marker of chronic kidney disease (CKD). Previous studies have shown that either metabolic syndrome (MetS) or chronic inflammation is related to renal impairment. The aim of this study was to investigate the association between MetS, C-reactive protein (CRP) and microalbuminuria in a rural Chinese population.MethodsThis was a cross-sectional study using data from the Handan Eye Study. MetS was defined according to the Chinese Diabetes Society (CDS) criteria. CRP levels ≥ 3 mg/L were classified as high CRP. Microalbuminuria was defined as a urinary albumin/creatinine ratio (ACR) of 30–300 mg/g.ResultsWe included 4191 subjects aged ≥ 30 years in this analysis. The prevalence of MetS and microalbuminuria in the group was 25.7% and 15.6%, respectively. The odds ratio (OR) of microalbuminuria in subjects with MetS was 1.25 (95% confidence interval (CI): 1.03 − 1.51) compared with those without microalbuminuria. In multivariate logistic regression analysis, high blood pressure (OR 1.36, 95% CI: 1.10 − 1.67) and high fasting blood glucose (OR 1.44, 95% CI: 1.17 − 1.76) were independently associated with microalbuminuria. Subjects with high CRP and MetS had a 1.46-fold greater risk of having microalbuminuria compared with those with low CRP without MetS (95% CI: 1.06 − 2.01).ConclusionsIn this rural Chinese population aged ≥30 years, MetS and microalbuminuria were independently related and the combination of high CRP and MetS was associated with an increased risk of microalbuminuria.

The Prevalence of and Risk Factors Associated with Pterygium in a Rural Adult Chinese Population: The Handan Eye Study

ABSTRACTPurpose: To describe the prevalence and risk factors for pterygium in a rural adult Chinese population.Methods: A total of 7557 people aged 30 years and over were randomly selected from 13 villages in a rural county, Yongnian, within Handan district, Hebei Province of China. All eligible subjects were invited to undergo a comprehensive eye examination. A slit-lamp was used to examine the anterior segment for evidence of pterygium. Pterygium was graded for severity (G1 to G3) by visibility of episcleral vessels.Results: Of 6685 participants (88.5% of 7557) included in this study, pterygium was present in 401 (6.0%). Using direct standardization to the 2000 China population census for rural residents, the prevalence of pterygium was 7.1% (95% confidence interval [CI], 6.5–7.8%) among subjects aged 40+ years, and 4.8% (95% CI 4.3–5.3%) when including those aged 30–39 years. Pterygium was more common in men than in women (age-adjusted odds ratio [OR] 2.0, 95% CI 1.4–2.8). Prevalence increased with age (OR 1.8, 95% CI 1.6–2.1 per decade increase in age). Current smoking appeared to be protective (OR 0.5, 95% CI 0.4–0.7). Of eyes with any pterygium, 4.6% (95% CI 1.9–7.3%) had low vision.Conclusion: Approximately one in ten adults had pterygium in this rural Chinese population. Age and male sex were positively, and current smoking negatively associated with the prevalence of pterygium.

Prevalence and Outcomes of Cataract Surgery in Adult Rural Chinese Populations of the Bai Nationality in Dali: The Yunnan Minority Eye Study

PurposeTo investigate the prevalence and visual acuity (VA) outcomes of cataract surgery in adults of the Bai Nationality populations in rural China.MethodsWe conducted a population-based cross-sectional survey (from randomly selected block groups) of Chinese Bai Nationality aged ≥50 years in southwestern China. Presenting visual acuity (PVA), best corrected visual acuity (BCVA) were recorded and a detailed eye examination was carried out. For all aphakic and pseudophakic subjects identified, information on the date, setting, type, and complications of cataract surgery were recorded. In eyes with VA <20/63, the principal cause of visual impairment was identified.ResultsOf 2133 (77.8% of 2742) subjects, 99 people (129 eyes) had undergone cataract surgery. The prevalence of cataract surgery was 4.6%. Surgical coverage among those with PVA <20/200 in both eyes because of cataract was 52.8%. Unoperated cataract was associated with older age. The main barrier to cataract surgery was lack of awareness and knowledge, cost, and fear. Among the 129 cataract-operated eyes, 22.5% had PVA of ≥20/32, 25.6% had PVA of 20/40 to 20/63, 23.3% had PVA <20/63 to 20/200, and 28.7% had PVA<20/200. With BCVA, the percentages were 42.6%, 23.3%, 10.9%, and 23.3%, respectively. Aphakia (odds ratio [OR], 8.49; P<0.001) and no education (OR, 10.18; P = 0.001) or less education (OR, 6.49; P = 0.014) were significantly associated with postoperative visual impairment defined by PVA, while aphakia (OR, 8.49; P<0.001) and female gender (OR, 4.19; P = 0.004) were significantly associated with postoperative visual impairment by BCVA. The main causes of postoperative visual impairment were refractive error, retinal disorders and glaucoma.ConclusionsHalf of those with bilateral visual impairment or blindness because of cataract remain in need of cataract surgery in Bai population. Surgical uptake and visual outcomes should be further improved in the future.

Growth of poor rural Chinese children fed meat as a daily complementary food from 6–18 months of age

ObjectiveTo determine the efficacy of a daily intake of meat as a complementary food from 6–18 mo on linear growth in a poor rural Chinese population.MethodsThe project was an unmasked RCT with cluster design in which 60 rural villages were randomly assigned to three groups. The daily interventions were 50g pork (M), equi‐caloric micronutrient‐fortified cereal‐based supplement (FC), and local non‐fortified rice supplement (UC) respectively. Anthropometry was performed at 6 and 18 mo.Results1465 subjects were enrolled at 6 mo of age (511M; 465 FC; 489 UC). At 18 mo old, 1317 subjects completed follow up (462 M; 436 FC; 419 UC). After adjustment for baseline values and mother's education levels, between M and FC, estimated Δ linear growth over 12 mo was 0.399 cm (95% CI: 0.163–0.636 cm, P=0.001), and LAZ was 0.137 (95% CI: 0.053–0.221, P=0.001) by pairwise comparisons. Mean (SD) LAZ, WAZ, &amp; WLZ are given in table.ConclusionMeat was associated with a significantly higher linear growth rate. However treatment group differences were small. Mean LAZ was low at 6 mo and declined further by 18 mo in all groups.Support: Thrasher Research Foundation; Sci &amp; Tech Commission of Shanghai Municipality; Shanghai Key Lab of Ped Gastroenter &amp; Nutr; Nat'l Natural Sci Foundation of China.

Screening for Parkinson syndrome in a Chinese rural population: re-examination of a historic questionnaire.

Standardized screening tools for Parkinson syndrome have not been developed for non-western populations. This study aimed to validate the Copiah County questionnaire (CCQ) as a screening instrument in a Chinese rural population. All participants of a previously reported prevalent study were interviewed using CCQ. The participants who answered yes to at least one item on CCQ were defined as positive. The Parkinson's disease (PD) diagnosis was established using United Kingdom Parkinson's disease Brain Bank Clinical diagnosis criteria (UKPDBBC) and served as a gold standard to determine the sensitivity, specificity, and positive and negative predictive values (PPV, NPV) for the questionnaire. Among 16 130 participants, 2872 (17.8%) were screened positive for CCQ and 13 258 negative (82.2%). Among the 697 participants diagnosed as having Parkinson syndrome, 605 were positive for CCQ, and 92 were negative, leading to a sensitivity of 86.8%. Out of the 15 433 non-Parkinson syndrome participants, 13 166 were negative to CCQ, giving a specificity of 85.3%. Among the 2872 participants screened positive, 605 were diagnosed with Parkinson syndrome, and their PPV was 21.1%. For the 13 258 participants screened negative on CCQ, 92 were diagnosed with Parkinson syndrome and 13 166 did not have Parkinson syndrome, leading to a NPV of 99.3%. CCQ appeared to have satisfactory statistical parameters to serve as a screening instrument for Parkinson syndrome in this rural Chinese population. Further studies may prove the utility of this short questionnaire in Parkinson syndrome screening among Chinese populations including those residing in rural areas.

Health literacy in rural areas of China: hypertension knowledge survey.

We conducted this study to determine levels and correlates of hypertension knowledge among rural Chinese adults, and to assess the association between knowledge levels and salty food consumption among hypertensive and non-hypertensive populations. This face-to-face cross sectional survey included 665 hypertensive and 854 non-hypertensive respondents in the rural areas of Heilongjiang province, China. Hypertension knowledge was assessed through a 10-item test; respondents received 10 points for each correct answer. Among respondents, the average hypertension knowledge score was 26 out of a maximum of 100 points for hypertensive and 20 for non-hypertensive respondents. Hypertension knowledge was associated with marital status, education, health status, periodically reading books, newspapers or other materials, history of blood pressure measurement, and attending hypertension educational sessions. Hypertension knowledge is extremely low in rural areas of China. Hypertension education programs should focus on marginal populations, such as individuals who are not married or illiterate to enhance their knowledge levels. Focusing on educational and literacy levels in conjunction with health education is important given illiteracy is still a prominent issue for the Chinese rural population.

Long-term effects of salt substitution on blood pressure in a rural North Chinese population

Dietary sodium and potassium intake can influence blood pressure. The effects of salt substitution on patients with hypertension and normotensive family member controls, however, have not been evaluated in a rural Chinese population. The objective of this study, accordingly, was to assess the long-term effects of salt substitution on blood pressure. We conducted a double-blind, randomized controlled trial among 200 families in rural China to establish the 2-year effects of a reduced-sodium, high-potassium salt substitute (65% sodium chloride, 25% potassium chloride, 10% magnesium sulfate) compared with normal salt (100% sodium chloride) on blood pressure. Of the 462 individuals in the trial, 372 completed the study (81%). For normotensive subjects, the mean overall difference in systolic and diastolic blood pressure between the two groups at the 24-month follow-up was 2 mm Hg (95% confidence interval (CI) 0-4 mm Hg, P<0.05) and 2 mm Hg (95% CI 1-3 mm Hg, P<0.05), respectively. For subjects with hypertension, the mean overall decrease in systolic blood pressure showed a 4-mm Hg (95% CI 2-6 mm Hg, P<0.05) decrease between the two groups. Diastolic blood pressure was not affected by salt use in the hypertensive group. Salt substitution lowers systolic blood pressure in hypertensive patients and lowers both systolic and diastolic blood pressure in normotensive controls. Salt substitution, therefore, may be an effective adjuvant therapy for hypertensive patients and the potential efficacy in preventing hypertension in normotensive individuals.

Abstract 9143: Mortality Resulting From Congenital Heart Diseases Through 2003 To 2010: A Population-based Study In China

BACKGROUND: Previous studies suggested that mortality from congenital heart diseases (CHD) is declining in the US. But we don't know what the CHD mortality trend is in China. What's more, we don't know whether the trends in rural and urban region follow different pattern or not in China, the largest developing country with rapid urbanization. This study aimed to determine recent changes in death caused by CHD in China and describe CHD mortality in rural and urban Chinese populations. METHODS: The data source was the China Ministry of Health 2003-2010 annual reports. Mortality was defined as death caused by CHD. Mortality rates for each year were calculated per 100,000 person-years. Poisson regression and descriptive analysis were conducted for overall trend and sub-group analysis was conducted by gender, age and urban/rural to understand potential disparities in mortality. RESULTS: From 2003-2010, the overall mortality rate increased from 141 per 100,000 person-years in 2003 to 229 in 2010, a 62.4% relative increase. This represents a region-sex adjusted annual increase of 9% (incidence rate ratio, 1.09; 95% CI, 1.09 to 1.10). The increase in CHD mortality was not uniformly observed across age groups, urban/rural and gender. The relative increases were 65.3%, 212.2% and 131.7% for age 1-10, 21-64 and 65 or older groups, respectively. Urban areas had a relative increase of 154.5% vs. 5.3% for rural areas. Female who lived in an urban environment had a relative increase of 313.5%. CONCLUSION: Different from US where the CHD mortality is reducing, our observation, based on Chinese Ministry of Health 2003-2010 annual reports, showed an obvious increasing trend of CHD mortality in China. What's more, increase in CHD mortality was not uniformly observed across age groups, urban/rural and gender. Such information is needed as a basis for working out and evaluating interventions and for the ongoing monitoring of CHD mortality and allocation of healthcare resources to properly treat CHD patients.

Psychometric Characteristics of the Duke Social Support Index in a Young Rural Chinese Population

The study is aimed to examine the psychometric characteristics of the Duke Social Support Scale (DSSI) in young rural Chinese individuals (379 suicides, 411 controls) aged 15–34 years. Social support was measured by 23-item DSSI, which included Social Interaction Scale, Subjective Social Support, and Instrumental Social Support. DSSI had high internal consistency (alphas all over .79) and correlated with hopelessness and anxiety in both samples. Confirmatory factor analysis showed that the structure models of DSSI were basically suitable for the original structure of DSSI but some items should be modified or deleted. Altogether, these findings support that DSSI has high reliability and validity, which makes it an acceptable measure for social support in young Chinese populations. However, further model tests should be carried out by deleting or modifying some items or being used in different populations.

Prevalence of and Risk Factors for Pterygium in Rural Adult Chinese Populations of the Bai Nationality in Dali: The Yunnan Minority Eye Study

The purpose of the study was to describe the prevalence, severity, and associated risk factors for pterygium in a population-based sample of rural residents of the Bai minority population in rural Dali, China. A population-based survey of Chinese Bai Nationality aged ≥50 years from randomly selected block groups in southwestern China was conducted. A clinical examination by experienced ophthalmologists was carried out, and the presence of pterygium was diagnosed at the examination. Pterygium was graded clinically by slit lamp examination. Questionnaires were conducted on risk factors. From a total of 2742 eligible subjects, 2133 (77.8%) were examined. The prevalence of pterygium was high (overall 39.0% [95% confidence interval (CI) 37.0-41.0]). Women had a higher rate than men (27.3% vs. 11.7%, respectively). In multivariate analysis, pterygium was independently associated with increasing age (odds ratio [OR] 1.55 [95% CI 1.24-1.93], 1.47 [95% CI 1.13-1.91], and 1.79 [95% CI 1.17-2.73], respectively, for persons 60-69 years, 70-79 years, and 80 years and older compared with 50-59 years), female sex (OR 1.42 [95% CI 1.08-1.88]), lack of formal education (OR 1.26 [95% CI 1.03-1.56]), and presence of outdoor work (OR 1.51 [95% CI 1.10-1.92]). Height, weight, hypertension, diabetes, smoking, and alcohol use history were not associated with pterygium. The prevalence of pterygium in Dali is 39.0% among Chinese Bai aged 50 years and older. Independent associations with increasing age (>59 years), female sex, lack of education, and occupations linked to outdoor work suggest a multifactorial cause of this condition.

Intraocular Pressure and its Relationship to Ocular and Systemic Factors in a Healthy Chinese Rural Population: The Handan Eye Study

Purpose: To describe the distribution of and factors related to intraocular pressure (IOP) in a healthy adult rural Chinese population in northern China.Methods: The Handan Eye Study is a cross-sectional, population-based study of eye diseases among 6,830 (90.4% response rate) rural Chinese persons aged 30+ years. Participants underwent an interviewer-administered questionnaire and a complete ocular examination, including standardized measurement of IOP with Perkins applanation tonometry.Results: After excluding persons with glaucoma, or those with diseases that have a marked effect on IOP or that preclude accurate IOP measurement, 6,101 persons were included in the current analysis. Mean IOP (mean ± standard deviation) of the study population was 15.0 ± 2.8 mmHg. Men had lower IOP than women (14.6 ± 2.8 mmHg versus 15.4 ± 2.7 mmHg, t = −8.37, P < 0.001). In the multivariate analysis younger age, female sex, presence of diabetes mellitus, higher blood pressure, higher body mass index, thicker central cornea and higher myopia were associated with higher IOP.Conclusions: Mean IOP among persons living in rural northern China was similar to that recently reported in southern China. IOP appeared to be lower with increasing age in Chinese subjects, which contrasts with results in white populations.

Associations between metabolic syndrome and syndrome components and retinal microvascular signs in a rural Chinese population: the Handan Eye Study

Our purpose was to determine the relationship of metabolic syndrome (MetS) and its components with retinal microvascular abnormalities in a rural Chinese population. The Handan Eye Study, a population-based survey, recruited 6,830 (90.4% of eligible) rural Chinese ≥30years of age. A diagnosis of metabolic syndrome was based on the International Diabetes Federation definition. Retinal microvascular signs and arteriolar and venular diameters were assessed from fundus photographs by graders who were trained at the Retinal Vascular Imaging Centre, University of Melbourne. After adjusting for age, gender, and smoking status, 5,519 participants with MetS, or with the specific components of large waist circumference, elevated blood pressure (BP), or elevated fasting blood glucose (FG), were more likely to have retinopathy, arteriovenous nicking, focal arteriolar narrowing, enhanced arteriolar wall reflex, and generalized retinal arteriolar narrowing than those without MetS or the corresponding component. Individuals with elevated triglycerides were significantly more likely to have arteriovenous nicking and retinopathy. These results show that individual components of MetS are associated with different retinal microvascular signs and with changes in retinal arteriolar and venular diameters.

Visual impairment and blindness in rural central India: the Central India Eye and Medical Study

The aim of the study was to investigate prevalence of visual impairment in rural central India. The population-based Central India Eye and Medical Study included 4711 subjects with an age of 30+ years. Presenting visual acuity (PRVA) and best-corrected visual acuity (BCVA) were recorded. Visual impairment and blindness were defined using the World Health Organization (WHO) standard and United States (US) standard. On the basis of PRVA and using WHO and US standards, 1049 [22%; 95% confidence interval (CI): 21.1, 23.5] subjects and 1290 (27%; 95% CI: 26.1, 28.7) subjects, respectively, were visually impaired, and 35 (0.7%; 95% CI: 0.5, 1.0) subjects and 116 (2.5%; 95% CI: 2.0, 2.9) subjects, respectively, were blind. The corresponding age-standardized prevalence figures were 17%, 21%, 0.5% and 2%, respectively. Using best-correcting glasses could eliminate PRVA-visual impairment/blindness in 729 subjects (67% of all subjects with visual impairment/blindness). On the basis of BCVA and using WHO and US standards, 333 (7%; 95% CI: 6.3, 7.8) subjects and 473 (10%; 95% CI: 9.2, 10.9) subjects, respectively, had visual impairment, and 22 (0.5%; 95% CI: 0.3, 0.7) and 31 (0.7%; 95% CI: 0.4, 0.9) subjects, respectively, were blind. Corresponding age-standardized prevalence figures were 5%, 8%, 0.4% and 0.5%, respectively. Causes for BCVA-visual impairment/blindness were cataract (75%), postoperative posterior capsular opacification (4%), surgical complications (2%), corneal opacifications (2%), age-related macular degeneration (2%), other macular diseases (1%), and glaucoma (1%). Age-standardized prevalence of PRVA-visual impairment/blindness (WHO definition) in the adult population of rural central India was 17%. Most frequent cause was undercorrected refractive error. Supply of correct glasses is the most efficient way to improve vision in the rural central India.

The Prevalence of Glaucoma in Adult Rural Chinese Populations of the Bai Nationality in Dali: The Yunnan Minority Eye Study

We evaluated the prevalence of glaucoma in adults of the Bai Nationality populations in rural China. A population-based survey of Chinese Bai Nationality aged ≥50 years from randomly selected block groups in southwestern China was conducted. Eligible persons were invited to local examination sites for a complete ophthalmic examination. Glaucoma was diagnosed using the International Society of Geographical and Epidemiological Ophthalmology Classification scheme. In the study, 2133 subjects (77.8% participation rate) were examined, with a crude prevalence of all glaucoma of 2.2% (95% confidence interval [CI] 1.6%-2.9%). Primary open angle glaucoma (POAG) was found in 1.0% of cases (95% CI 0.6%-1.6%) and primary angle-closure glaucoma (PACG) in 0.9% (95% CI 0.6%-1.4%). The prevalence of all glaucoma was significantly higher in older people and women. Mean intraocular pressure (IOP) was 16.17 ± 3.74 mm Hg (97.5th and 99.5th percentiles, 24 mm Hg and 30 mm Hg, respectively). The mean vertical cup-to-disc ratio (VCDR) was 0.43 ± 0.17 (97.5th and 99.5th percentiles 0.7 and 0.8, respectively). Unilateral blindness was found in 80% of PACG, compared to only 36.3% of POAG cases. Prevalence of POAG is similar to PACG in the ethnic Bai population living in rural southwestern China. PACG has a worse visual impairment and prognosis compared to POAG.

Prevalence and associations of cataract in a rural Chinese adult population: the Handan Eye Study

Cataract remains the leading cause of blindness and visual impairment in the world and in China. However, data on the prevalence of cataract based on standardized lens grading protocols from mainland China are limited. This paper estimated the age- and gender-specific prevalence and risk factor for cataract In a population-based Chinese sample, participants underwent a comprehensive ophthalmic examination, including assessment of cortical, nuclear, posterior subcapsular (PSC) and mixed lens opacities from slit-lamp grading using the Lens Opacities Classification System III. Of the 7,557 eligible subjects, 6,830 took part in the study (90.4% response rate), and 6,544 participants (95.8%, mean age 52.0 ± 11.8 years) had lens data for analyses. The prevalence of any cataract surgery in at least one eye was 0.8% (95% confidence interval [CI], 0.62, 1.06), with similar rates between men and women. The overall prevalence of any cataract or cataract surgery was 20.8% (95% CI, 19.8, 21.8), higher in women than in men after adjusting for age (23.6% vs 17.6%; OR: 1.78; 95% CI: 1.54-2.07). When distinct lens opacity was categorized in each eye as cortical, nuclear, PSC or mixed, based on one randomly selected eye, cortical cataract was the most common distinct subtype (12.3%), followed by mixed (3.2%), nuclear (1.7%), and PSC (0.2%) cataract. The prevalence of all lens opacities increased with age (P < 0.001). After excluding other causes for visual impairment, the proportion of people with best corrected visual acuity <20/60 was 21% among those with PSC, and 12% among those with mixed opacities in the better-seeing eye. In multivariable logistic regression models, myopia was associated with all cataract types, while higher fasting plasma glucose and diabetes were only associated with PSC cataract. Cataract affects 20% of the population aged 30 years and older living in rural China, with cortical cataract the most common subtype. Risk factors for cataract include myopia and diabetes.

Household Water Treatment in China

This study was supported by the Bill & Melinda Gates Foundation, under grant reference 48599 (Aquatest 2: Delivery a low cost water test for developing countries). Dear Sir: We read with interest the article by Rosa and Clasen1 about the prevalence of household water treatment in low-income and middle-income countries. They discussed the geographic limitations of their global estimation, especially the lack of data for the largest national population in China. Several surveys covering water and sanitation have been undertaken in China in recent decades, such as the World Health Survey, the Global Water Supply and Sanitation Assessment 2000, and the Multiple Indicator Cluster Survey. These survey results have already been included in the World Health Organization/United Nations Children's Fund Joint Monitoring Program report.2 However, none of these survey questionnaires covered household water treatment. Despite the lack of data on home water treatment accessible in the English language, it is possible that other surveys exist that have been conducted by the Chinese government rather than through international systems, such as the Multiple Indicator Cluster Survey, with results published in Chinese only. We searched the bibliographic database Chinese National Knowledge Infrastructure by using the Chinese key words for “household” and “water” and “treatment/disinfection”. We found 417 Chinese language references. After screening the titles and abstracts of all references and the content of an additional 197 references, we found one paper reporting the national summary results of the Investigation of Drinking Water and Sanitation in the Rural Areas conducted jointly by the Ministry of Health and the National Committee for Patriotic Public Health Campaign, People's Republic of China, during August 2006–November 2007.3 In this nationally representative multi-stage cluster survey of rural areas, 6,948 sites were surveyed in 6,590 villages across all 31 provinces, autonomous regions, and municipalities in mainland China. A total of 65,839 households were interviewed and 6,948 supply system, groundwater and surface water samples were tested for physicochemical parameters and total coliforms. The interviews included two questions on home water treatment: • “What is your usual drinking practice? 1) Drink raw water, 2) Drink boiled water” and • “Do you treat (other than boiling) the household?s water? Yes or No”. Although the raw data are still not publicly available, the summary of the official report indicated that 85.23% of rural households boiled their water before drinking and 5.11% treated their water (excluding boiling).3 Given that the mainland Chinese rural population was estimated to be 712.88 million in 2009,4 this finding suggests that the population boiling household water is 607.59 million and the population using other forms of home water treatment is 36.3 million in rural China. Household water filters are increasingly used in urban areas of China. Although there are no reported household survey data for urban areas, one report estimated that 3–5% of the urban population used household water filters.5 If this 4% prevalence estimate for household water filtration is applied to the total mainland Chinese urban population of 621.86 million,4 this suggests a population of 24.9 million filtering their water. Including these estimates for China, the global population from low-income and middle-income countries boiling household water doubles from 0.601 to 1.21 billion, and the population using treated household water increases to at least 1.78 billion. A small-scale survey in Anhui Province in central China that collected 35 household storage water samples from randomly selected households in three counties reported that the compliance rate for total coliforms (< 1 colony-forming unit/100 mL) of water stored in the home was only 39%.6 This limited evidence on microbial contamination of stored water implies that there may be a need for household water treatment in rural China. Other treatment methods, e.g., filters, are increasingly used in more economically developed parts of rural China.7 However, boiling is still the most widely used water treatment method in rural China. The Investigation of Drinking Water and Sanitation in the Rural Areas survey figures illustrate the need for more data on the world's most populous nation in understanding global patterns of household water treatment. It further underscores the need articulated by Rosa and Clasen to understand the effectiveness and use of boiling in non-intervention settings.