The health status of diabetic patients receiving orthotic therapy

Diabetes has a major impact on the quality of life and those with related foot ulcers are among those most affected. The main aim of the study, which was carried out over an 18-month time period, was to compare the self-reported health status of a group of diabetic patients receiving orthotic therapy with that of other groups who did not receive the therapy. A sample of 280 was recruited from patients with type I and type II diabetes. The study group comprised four groups of patients: those receiving orthotic therapy (insoles) for pedal complications as a result of their diabetes; those with diabetes mellitus, without complications of the disease affecting their foot; those with unilateral lower limb amputation and those with active ulceration who had not been prescribed footwear. The specialised orthotic intervention resulted in statistically significant improvements in health status (p < 0.05), (measured using the SF-36) both physically and mentally, for patients with at-risk feet and should become an integral part of the treatment regime for diabetics with at-risk feet.     

The MOS SF-36 health survey questionnaire in severe chronic airflow limitation: Comparison with the Nottingham health profile

This study documents the cross-sectional, health-related quality of life (HRQOL) measures obtained at baseline for patients with severe chronic airways limitation (CAL) being assessed for home oxygen therapy (HOT) at the Flinders Medical Centre, Adelaide, South Australia. Two generic quality of life instruments, the Nottingham Health Profile (NHP) and the Medical Outcomes Study (MOS) short form 36-item questionnaire (SF-36), were administered by interview to the same patients to permit comparisons to be made between the two instruments. SF-36 mean scores were also compared with scores obtained in separate studies of a South Australian elderly general population and of groups of Australian subjects with various medical and psychiatric conditions. NHP mean scores were compared with scores from an elderly group of Adelaide residents from a household survey. HRQOL measures were obtained for 60 patients, 32 males and 28 females. At assessment for HOT, patients with severe CAL were experiencing severe impairment in their quality of life in comparison to age-matched South Australian norms, with physical disability the major limitation. There were several significant correlations between the domains of the SF-36 and the NHP which were predominantly gender-specific. Only small decrements in mental health were found with the SF-36 questionnaire. The SF-36 and the NHP appear to provide discrepant information for severely disabled CAL patients for the subjective domains of emotional and mental health.     

The SF-36 questionnaire and its usefulness in population studies: results of the German Health Interview and Examination Survey 1998

SummaryObjectives To describe the distribution and the relationships of the SF-36 scales in a representative sample of the German population.Methods The German National Health Interview and Examination Survey 1998 comprised 7 124 participants aged 18 to 79 years and included the Short Form 36 Questionnaire (SF-36). The 1998 findings are compared to those of the first normative German SF-36 sample from 1994.Results Older people ( 65 years) in particular have increased the mean scale values for quality-of-life assessment during the four years. The average of all SF-36 scales increases with the social status of the individual in all age categories. The representative sample shows a more positive subjective assessment of their quality-of-life by East Germans in nearly all scales of SF-36, although they do not have a correspondingly better health status. The intensity of pain and the number of diseases during the preceding year are shown to decrease the life quality scales. Furthermore the General Health scale of SF-36 is correlated with the physicians' consultation.Conclusion The instrument to assess quality-of-life can generate useful information for a wide variety of variables. However, future health-related quality-of-life measurements in healthy population should be more sensitive and more differentiating than the SF-36 instruments.

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ZusammenfassungFragestellung Die Beschreibung der Verteilung der Skalen des SF-36-Fragebogens in einer repräsentativen Bevölkerungserhebung.Methoden Beim deutschen Bundes-Gesundheitssurvey 1998 nahmen 7 124 Probanden im Alter zwischen 18 und 79 Jahren teil. Erstmals wurde der SF-36 (Short Form 36)-Fragebogen eingesetzt. Die Ergebnisse von 1998 werden mit der SF-36-Normstichprobe von 1994 verglichen.Ergebnisse Insbesondere für ältere Menschen (65 Jahre) sind die mittleren Werte der Lebensqualitätsskalen in den letzten vier Jahren gestiegen. Die Mittelwerte der SF-36-Skalen erhöhen sich ausserdem mit dem Sozialstatus in allen Altersgruppen. Die repräsentative Stichprobe zeigt zudem für fast alle Skalen eine bessere subjektive Einschätzung der gesundheitsbezogenen Lebensqualität bei den Ostdeutschen, obwohl sie objektiv gesehen keinen besseren Gesundheitszustand aufzuweisen haben. Die Intensität von Schmerz und die Zahl von Krankheiten im vorangegangenen Jahr verringern die Werte der Lebensqualitätsskalen. Ausserdem besteht ein Zusammenhang zwischen der Inanspruchnahme von ärztlichen Leistungen und der subjektiven Einschätzung der allgemeinen Gesundheit.Schlussfolgerung Durch Untersuchung sehr unterschiedlicher Fragestellungen werden die Sinnhaftigkeit und der Informationswert dieses Lebensqualitätsinstruments klar demonstriert. Dennoch müssen die Instrumente zur Messung der gesundheitsbezogenen Lebensqualität für die gesunde Bevölkerung künftig sensitiver und differenzierter werden als es der SF-36 gegenwärtig zu sein vermag.

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RésuméObjectifs Décrire la distribution des échelles du questionnaire SF-36 dans une enquête représentatif de la population allemande.Méthodes En Allemagne, 7 124 personnes entre 18 et 79 ans ont participé à l'enquête Nationale de Santé 1998 qui incluait pour la première fois le questionnaire SF-36 (Short Form 36). Les résultats de 1998 sont comparés à ceux du premier échantillon standardisé de 1994.Résultats Il est démontré que les moyennes des valeurs d'échelles de la qualité de vie ont augmenté en particulier chez les vieilles personnes pendant les quatre années précédentes. De plus les moyennes de toutes les échelles SF-36 augmentent avec le statut social des individus dans toutes les catégories d'âge. Le tirage représentatif montre en outre une estimation subjective de la qualité de vie plus positive pour les Allemands de l'Est en comparaison avec les Allemands de l'Ouest, bien qu'objectivement ils n'aient pas un état de santé supérieur. Il est démontré que l'intensité de la douleur et le nombre de maladies durant l'année précédente diminuent les valeurs des échelles de qualité de vie. De plus, l'estimation générale subjective de la santé est corrélée avec le nombre de visites chez des médecins.Conclusions L'nstrument d'évaluation de la qualité de vie peut générer des informations utiles pour toute une série de variables. Cependant les instruments de mesure de la qualité de vie relative à la santé utilisés pour la population en bonne santé devraient à l'avenir devenir plus sensibles et plus pointus que les instruments SF-36.

     

Testing the validity of the Euroqol and comparing it with the SF-36 health survey questionnaire

There is an interest in the consequences of deriving a single index measure of health for validity and sensitivity. This paper presents the results of testing a recent example of a general health measure designed to derive a single index, the Euroqol (EQ), and presents a comparison with a new, influential profile measure, the Short Form 36 (SF-36) Health Survey Instrument. The EQ and an anglicised version of the SF-36 health survey, both designed for self-completion, were included in a postal survey of a random sample of 1980 patients from two practice lists in Sheffield, UK. The response rate for the EQ questionnaire was 83%, and the rate of completion over 95%. Evidence was found for the construct validity of the EQ dimension responses and the derived total EQ health score in terms of distinguishing between groups with expected health differences. Considerable agreement was found between EQ responses and the total EQ score, and the UK SF-36 profile scores. There was substantial evidence of EQ being less sensitive at the ceiling (i.e. low levels of perceived ill-health) and throughout the range of health states. A recent restructuring of the EQ, may help overcome some of the problems with the physical dimensions by reducing their skewness.     

Self-rated health in persons with spinal cord injury: relationship of secondary conditions, function and health status

Objective  Self-rated health is used frequently as a measure of health in the general population, and increasingly with persons with disabilities. However, its meaning and its relationship with other measures of self-reported health (health status and secondary conditions) are not well understood for this group. The purpose of the present study was to use a conceptual model to examine the structure of self-rated health with persons with spinal cord injuries. Methods  A US sample of 270 adults with mobility impairment stemming from spinal cord injury (SCI) provided data on three measures of self-reported health that differ in degree of subjectivity: physical problems common to SCI, four domains of health status from the SF-36, and a single item on self-rated health. Data were compared with the norm sample of the SF-36. The conceptual model was tested using path analyses. Results  SF-36 scores were lower on three of four domains compared with the norm sample. The conceptual model analyses indicated that 35% of variance in self-rated health is accounted for through direct relationship with physical secondary conditions common to persons with SCI and as mediated through SF-36 domains of Role Physical and Vitality. The SF-36 domain of Physical Function was statistically unrelated to self-rated health. Conclusion  The conceptual model of self-rated health was verified in a sample of persons with SCI. Importantly, the SF-36 domain of Physical Function does not relate to self-rated health for this group. Its inclusion in measures of self-reported for disability populations creates difficulty without apparent benefit.     

Patient-based health status measurement in clinical practice: a study of its impact on epilepsy patients' care

The objective was to assess the potential benefits of the routine use of the MOS SF-36 Health Survey (SF-36) in the care of ambulatory patients. The design was a longitudinal, prospective, randomized, controlled study set in the outpatient neurology clinic at the New England Medical Center. There were 163 consecutive patients with epilepsy who had 210 follow-up visits with one of two epileptologists. The patients completed the SF-36 before the patient-physician encounter and the forms were optically scanned. The SF-36 results of the intervention group patients were given to the physicians before the encounter and withheld for control group patients. For intervention group patients, the physicians completed a questionnaire assessing the impact of the SF-36 on the process of care. After the visit, all patients completed a satisfaction questionnaire. The main outcome measures were the physicians' responses to standardized questions about the usefulness of the SF-36 for communication with and management of epilepsy patients and the patients' responses to standardized questions about their satisfaction with care. The physicians indicated that the SF-36 provided new information in 63% of the intervention group encounters. A change in therapy was prompted in 13%. The physicians rated the SF-36 as at least moderately useful for communication in 14% of the encounters and to management in 8%. The lower (indicating worse health status) the patients' SF-36 scale scores, the more useful the SF-36 results were rated by the physicians for communication and management. It was concluded that the routine use of health status measures may enhance patients' care.     

慢性丙型肝炎患者1129例感染途径流行病学分析

目的了解慢性丙型肝炎患者感染途径并进行流行病学分析,为中国慢性丙型肝炎的预防提供基础资料。方法本研究采用问卷的形式,调查患者的年龄、性别、感染途径等,并进行流行病学分析。结果 1 129例慢性丙型肝炎患者中,输血及血制品感染者,占61.2%,感染途径不详者占32.8%,吸毒者3.9%;与丙肝患者密切接触者1.6%,性行为0.5%;不同性别间感染途径比较差异有统计学意义,(χ²=36.695,P<0.01);不同年龄段感染途径比较差异有统计学意义,(χ²=98.281,P<0.01);南北方城市感染途径比较差异有统计学意义,(χ²=34.594,P<0.01)。结论慢性丙型肝炎的感染途径主要以输血及血制品使用为主,不同性别、年龄段、地域慢性丙型肝炎的感染途径存在明显差异。     

Physical functioning and mental health in patients with chronic medical conditions

There is evidence to suggest that a decline in physical functioning with advancing age is independent of mental health, which appears to remain relatively stable. There is additional evidence to suggest that those with a chronic disease also experience a decline in physical function while the mental health remains relatively stable. Using a cross-sectional design, data from the US population norms for the Medical Outcomes Study SF-36 are examined and compared to SF-36 data collected for four patient groups. Patient groups include kidney dialysis patients, multiple sclerosis patients, kidney transplant patients and patients with severe osteoarthritis of the hip prior to total hip replacement. Overall scores and scores within 10-year age groupings are examined in order to compare the physical functioning and mental health scores of the general population with those of the four patient groups. Results support the hypothesis that physical functioning declines with advancing age and with the development of chronic disease, but mental health remains remarkably stable regardless of chronic disease and/or advancing age. This observation suggests a process of psychological adjustment or adaptation to the physical difficulties encountered with advanced age or disability, and implies that this adjustment process may in fact be quite strong.     

A Kiswahili version of the SF-36 Health Survey for use in Tanzania: translation and tests of scaling assumptions

The objective of the study was to translate and adapt the SF-36 Health Survey for use in Tanzania and to test the psychometric properties of the Kiswahili SF-36. A cross-sectional study was conducted as part of a household survey of a representative sample of the adult population of Dar es Salaam, Tanzania. The IQOLA method of forward and backward translation was used to translate the SF-36 into Kiswahili. The translated questionnaire was administered by trained interviewers to 3,802 adults (50% women, mean (SD) age 31 (13) years, 50% married and 60% with primary education). Data quality and psychometric assumptions underlying the scoring of the eight SF-36 scales were evaluated for the entire sample and separately for the least educated subgroup (n=402), using multitrait scaling analysis. Forward and backward translation procedures resulted in a Kiswahili SF-36 that was considered conceptually equivalent to the US English SF-36. Data quality was excellent: only 1.2% of respondents were excluded because they answered less than half of the items for one or more scales; ninety percent of respondents answered mutually exclusive items consistently. Median item–scale correlations across the eight scales ranged from 0.47 to 0.81 for the entire sample. Median scaling success rates were 100% (range 87.5–100.0). The median internal consistency reliability of the eight scales for the entire sample was 0.81 (range 0.70–0.92). Floor effects were low and ceiling effects were high on five of the eight scales. Results for n=402 people without formal education did not differ substantially from those of the entire sample. The results of data quality and psychometric tests support the scoring of the eight scales using standard scoring algorithms. The Kiswahili translation of the SF-36 may be useful in estimating the health of people in Dar es Salaam. Evidence for the validity of the SF-36 for use in Tanzania needs to be accumulated.     

孕产期健康教育与产褥期妇女生命质量调查

目的:探讨产褥期妇女生命质量状况。方法:应用MOSSF-36健康调查量表和自制母婴保健知识调查问卷对555例产后42天回医院检查的产妇进行问卷调查。结果:产褥期妇女生命质量整体状况较好,社会功能、生理机能、精神健康、躯体疼痛4个维度水平较高,生理职能、情感职能2个维度水平较低。接受健康教育不同,产褥期妇女生命质量有所不同,系统健康教育组与非系统健康教育组比较在社会功能和精神健康2个维度得分低,差异具有统计学意义(P<0.01、P<0.05)。非系统健康教育组产妇阴道炎、子宫颈糜烂的发生率较高。结论:产前接受健康教育程度、产褥期母婴保健知识和护理能力会影响产褥期妇女的生命质量。     

健康教育对慢性乙型肝炎合并抑郁症患者的影响

目的调查慢性乙型肝炎患者抑郁症状发生率并探讨健康教育对抑郁症状及肝功能的影响。方法采用Zung抑郁自评量表(SDS)对106例慢性乙型肝炎患者进行测评。将抑郁指数≥0.5的56例患者随机分为干预组28例,对照组28例。干预组在住院期间药物治疗的同时并进行健康教育与心理社会干预,分别于入出院时SDS、肝功能、HBV DNA检测,对病情恢复时间进行评估。结果慢性乙型肝炎并抑郁情绪检出率为52.83%,SDS总分均值54.98±10.50,与国内常模比较,高度显著性差异(P<0.01),经健康教育与心理社会干预后,干预组抑郁指数显著降低(P<0.01),病情恢复时间(肝功能、HBV DNA复常时间)显著缩短(P<0.05)。结论慢性乙型肝炎患者常合并忧郁症状,健康教育与心理社会干预可改善抑郁症状及机体的免疫功能,提高抗病毒能力。     

Sleep problems, health-related quality of life, work functioning and health care utilization among the chronically ill

Objectives: To provide a comprehensive assessment of whether sleep problems among the chronically ill are associated with decrements in functional health and well-being, decreases in work functioning and increases in the use of health care services. Design: Cross-sectional survey of patients from the Medical Outcomes Study (MOS), an observational study of functional health and well-being. Chronically ill patients (n = 3484) were sampled from health maintenance organizations, large multi-specialty groups, and solo or single-specialty group practices in Boston, Los Angeles, and Chicago. Chronic illness subgroups include: clinical depression (n = 527), congestive heart failure (229), diabetes (n = 577), recent myocardial infarction (n = 170), hypertension (n = 2206), asthma (n = 84), back problems (n = 771), and arthritis (n = 672). ANCOVA analyses of the relationship between sleep problems and SF-36 scales and summaries were performed. In addition, a ‘relative impact’ analysis determined what scales or summaries were most associated with sleep problems. Main outcome measures: Eight scales and two summary measures from the SF-36 Health Survey, work productivity and work quality measures and self-reports of health care utilization. Results: Comparing chronically ill patients with no sleep problems to those with mild, moderate, or severe sleep problems revealed a direct association between sleep problems and decrements in health-related quality of life (HRQOL) as measured by SF-36 scales and summaries (MANOVA F 24.1; d.f. 24; p ≤ 0.0001). In addition, significant differences in HRQOL were found when comparing patients with and without sleep problems within most of the disease groups studied. The relative impact analysis revealed that measures of mental health and the mental health summary were most associated with sleep problem severity in the total sample and chronic disease subsets, in comparison with measures of physical health. In addition, monotonic relationships were found between severity of sleep problems and decreases in work productivity and increases in health care utilization, as expected. Conclusions: The analyses revealed that sleep problems go hand in hand with poorer mental health, diminished work productivity and work quality and greater use of health care services. Sleep problems, therefore, may be a significant confounding factor in the interpretation of health outcomes among patients with chronic diseases. This revised version was published online in June 2006 with corrections to the Cover Date.     

A comparison of the responsiveness of different generic health status measures in patients with asthma

Generic health status has been recommended to be measured separately from disease-specific health status, because they can yield complementary information. In particular, generic health status can provide comprehensive health ratings across various disorders. However, the weakness with generic measures is that they may be less responsive to clinical changes than disease-specific ones. Therefore, when using generic health status as an endpoint in clinical trials, the instrument to be used is a problem with respect to responsiveness. In the present study, we investigated and compared the responsiveness of health status measures during asthma treatment using three different generic instruments: the Medical Outcomes Study Short Form 36-items Health Survey (SF-36), the Nottingham Health Profile (NHP) and the EQ5D (EuroQoL), as well as one disease-specific instrument, the Asthma Quality of Life Questionnaire (AQLQ). Fifty-four new patients with asthma who consulted our clinic were recruited. The health status measurements were performed on the initial visit, and at 3 and 6 months. All subscales of the SF-36 showed a significant improvement during the first 6 months. Each dimension of the EQ5D showed stronger ceiling effects than the SF-36. With respect to the responsiveness indices, the SF-36 was regarded as more responsive than the NHP or EQ5D utility. The changes in the SF-36 had a weak to moderate correlation with the changes in the AQLQ. In conclusion, the SF-36 had a higher responsiveness for asthma as a generic measure than the NHP or EQ5D, and evaluated different aspects from the AQLQ. The SF-36 can be used effectively in asthma clinical trials.     

慢性丙型病毒性肝炎患者医院感染调查研究

目的调查慢性丙型病毒性肝炎患者医院感染情况及其危险因素。方法对2001年7月-2004年7月间189例住院慢性丙型肝炎病毒（HCV）感染患者的临床资料进行回顾性分析。结果189例慢性HCV感染患者医院感染率为21．69％；感染部位以腹腔（41．46％）和呼吸道（26．83％）为主；慢性丙型重型肝炎患者医院感染率为58．14％，慢性丙型重、中、轻度肝炎患者医院感染率分别为21．57％，7．55％，2．38％；导尿和腹水蛋白≤10g／L是其医院感染危险因素。结论慢性丙型病毒性肝炎患者医院感染率高，且病程越长，病情越重，处于危险因素中，医院感染率越高。     

The influence of decisions made by developers on health status questionnaire content

To investigate the effect of stringent and lenient criteria upon the process of item selection in the development of a health status questionnaire, an item pool (179 items) was administered to 139 patients with left ventricular dysfunction. Associations between each item and the criteria of gender, age, duration of disease, global health and global impairment were examined. Items were selected from the pool on the basis of their associations with the criteria using four levels of stringency. The most stringent criteria rejected items which had a shared variance of 4% with gender, age and duration of disease and a shared variance of 6% with global health and impairment. The most lenient criteria rejected items which had a shared variance of 6% with gender, age and duration of disease and a shared variance of 4% with global health and impairment. Using the most stringent criteria, 75 items were selected, compared with 127 items using the most lenient criteria. Small differences in the level of association had large effects on item selection. The choice of level of association used to base item selection can have a crucial influence on questionnaire content.     

Do differences in methods for constructing SF-36 physical and mental health summary measures change their associations with chronic medical conditions and utilization?

Background and objective: Various approaches have been employed to derive physical health and mental health summary scores for the SF-36 and the RAND-36, but head-to-head comparisons of alternative scoring algorithms are rare. We determined whether the associations of the physical and mental health summary scores with chronic medical conditions and utilization would differ depending on the scoring algorithm used. Methods: We examined 5701 patients receiving medical care from an independent association of 48 physician groups located primarily in the western United States and compared SF-36 and RAND-36 scoring of physical health and mental health summary scores. Associations with the presence of diabetes, heart disease, and kidney disease, as well as with utilization of medical care and mental health care were compared using bivariate and multivariate analysis. To examine the relationship between SF-36 and RAND-36 scores, we regressed the SF-36 physical and mental health composite scores on the RAND-36 physical and mental health summary measures and vice versa. Results: We found that the SF-36 and RAND-36 summary scores generally yielded results similar to one another across measures of heart disease, diabetes, and kidney disease, as well as measures of utilization. However, for each chronic medical condition, the RAND-36 showed a slightly larger decrement in mental health than did the SF-36. Conclusions: Differences between the two sets of summary scores were consistent with their respective conceptual and analytic approaches. Where comparisons of results between the SF-36 and RAND-36 summary scores are desirable in future studies, they can be estimated using the regression equations derived in this study.     

SF-36量表用于晚期血吸虫病患者生命质量的评价

晚期血吸虫病(晚血)是一种严重危害人民身体健康~([1]),制约疫区经济发的地言性寄生虫病,也是血防工作的重点和难点之一.     

The feasibility and responsiveness of the health utilities index in patients with early-stage breast cancer: A prospective longitudinal study

Background The health utilities index (HUI3) is a health measurement instrument based on individuals’ preferences for different health states. Breast cancer (BC) is common, with a high proportion of long-term survivors, making evaluation of treatment effects important. Feasibility and responsiveness of HUI3 was compared to the short-form 36 (SF-36) in patients with BC. Methods HUI3 and SF-36 were administered eight times: at initial surgical consultation, 1 week before surgery; 1 week, 3, 6, 12, 18, and 24 months after surgery. Effect size, analysis of variance, and Pearson product moment correlations were calculated. BC data were compared to normative values. Results Eighty-five patients were enrolled. Ninety-one percent of planned assessments were completed. HUI3 showed significant responsiveness (P < 0.01) after surgery and during recovery. HUI3 scores correlated with SF-36 scores. Comparison to normative data demonstrated the significant detrimental effect of BC diagnosis. Results showed long-term effects of treatment on physical health and positive effects on mental/emotional health in BC survivors. Conclusion(s) HUI3 was found to be feasible and responsive in our cohort of BC patients. Changes in HUI3 values over time, and compared to normative data, paralleled SF-36 scores. HUI3 is a valuable tool in health-related quality of life and cost-utility studies in patients with BC.     

慢性丙型肝炎患者抑郁焦虑状况及影响因素分析

目的 探究昆明市慢性丙型肝炎患者抑郁、焦虑状况及影响因素。方法 随机选取2013年1月至2018年12月昆明市传染病监测系统报告的慢性丙型肝炎患者480例作为研究对象,采用焦虑自评量表（SAS）与抑郁自评量表（SDS）评估慢性丙型肝炎患者抑郁、焦虑程度,通过单因素分析与Logistic回归分析筛选影响患者抑郁、焦虑的相关因素。结果 480例慢性丙型肝炎患者中男/女为320/160,平均年龄（45.40±3.72）岁,病程0.5~12.0年,平均（7.63±2.45）年。患者SDS评分为（47.81±9.69）分、SAS评分为（42.62±9.53）分,其中SDS≥53分的有124例（25.83%）,SAS≥50分的有110例（22.92%）。Logistic回归分析显示：初中及以下文化程度（OR=2.986）、中间型性格（OR=1.895）、内向型性格（OR=1.869）、人均月收入<1 000元（OR=3.735）、感到被歧视（OR=1.447）是影响患者抑郁的独立危险因素,知晓预防措施（OR=0.326）为保护因素;中间型性格（OR=1.957）、内向型性格（OR=2.043）及感到被歧视（OR=1.862）是影响患者焦虑的危险因素,知晓预防措施（OR=0.387）为保护因素。结论 昆明市慢性丙型肝炎患者抑郁、焦虑评分处于较高水平,文化程度低、性格内向、收入低、感到被歧视是影响抑郁、焦虑的危险因素,知晓预防措施为保护性因素。