Respondent-driven sampling (RDS) is a method of sampling specifically for hidden populations, often applied to transgender women, female sex workers, men who have sex with men, and other groups that are difficult to identify and contact because of stigma and legal constraints. However, this method is gradually applied to the general population. With the continuous improvement of RDS, studies find that the network size of RDS samples can be weighted to estimate the overall situation and population size. This article summarizes the current application progress of RDS in population size estimation and provides ideas for the development of RDS and the use of RDS to carry out relevant research.
Female ; HIV Infections/epidemiology* ; Homosexuality, Male ; Humans ; Male ; Population Density ; Sampling Studies ; Sex Workers ; Sexual and Gender Minorities ; Surveys and Questionnaires

Adenosine Monophosphate ; analogs & derivatives ; therapeutic use ; Adult ; Aged ; Alanine ; analogs & derivatives ; therapeutic use ; Anti-Arrhythmia Agents ; therapeutic use ; Arrhythmias, Cardiac ; diagnosis ; epidemiology ; Coronavirus Infections ; diagnosis ; drug therapy ; epidemiology ; Echocardiography ; Electrocardiography ; methods ; statistics & numerical data ; Female ; Follow-Up Studies ; Humans ; Male ; Pandemics ; statistics & numerical data ; Pneumonia, Viral ; diagnosis ; drug therapy ; epidemiology ; Sampling Studies ; Severe Acute Respiratory Syndrome ; diagnosis ; epidemiology ; Singapore ; Treatment Outcome

No abstract available.
Statistics as Topic ; Models, Statistical ; Data Interpretation, Statistical ; Sampling Studies ; Biometry

BACKGROUND: Under certain situations, women with twin pregnancies may be counseled to undergo invasive prenatal diagnostic testing. Chorionic villus sampling and amniocentesis are the two generally performed invasive prenatal diagnostic tests. Studies comparing procedure-related fetal loss between first-trimester chorionic villus sampling and second-trimester amniocentesis in twin pregnancies are limited. This study aimed to evaluate the procedure-related fetal loss and the obstetrical outcomes of these two procedures, chorionic villus sampling and amniocentesis in twin pregnancies. METHODS: The data from dichorionic-diamniotic twin pregnancies on which first-trimester chorionic villus sampling (n = 54) or second-trimester amniocentesis (n = 170) was performed between December 2006 and January 2017 in a single center were retrospectively analyzed. The procedure-related fetal loss was classified as loss of one or all fetuses within 4 weeks of procedure, and overall fetal loss was classified as loss of one or all fetuses during the gestation. The groups were compared with respect to the procedure-related and obstetrical outcomes. RESULTS: The difference in proportion of procedure-related fetal loss rate (1.9% for chorionic villus sampling vs. 1.8% for amniocentesis; P = 1.000) and the overall fetal loss rate (7.4% for chorionic villus sampling vs. 4.7% for amniocentesis; P = 0.489) between the two groups was not significant. The mean gestational ages at delivery were not statistically significant. CONCLUSION: Both the overall fetal loss rate and the procedure-related fetal loss rate of chorionic villus sampling and amniocentesis in dichorionic twin pregnancies had no statistical significance. Both procedures can be safely used individually.
Amniocentesis ; Chorion ; Chorionic Villi Sampling ; Chorionic Villi ; Diagnostic Tests, Routine ; Female ; Fetus ; Gestational Age ; Humans ; Pregnancy ; Pregnancy, Twin ; Retrospective Studies ; Twins

OBJECTIVE: In 2007, the American College of Obstetricians and Gynecologists (ACOG) recommended that all pregnant women be offered screening or diagnostic tests for chromosomal abnormalities regardless of their age. Noninvasive prenatal testing (NIPT) for common chromosomal aneuploidies was introduced as a screening test in case of high-risk pregnancies. We assessed the rates of prenatal tests in women aged 35 years and older. METHODS: A retrospective study was conducted to compare the rates of amniocentesis, chorionic villus sampling (CVS), serum screening, and NIPT from January 2005 through March 2017 in women aged 35 years and older. We divided the initial 12 months after NIPT introduction into 4-month intervals, beginning in April 2016 through March 2017. RESULTS: The rates of amniocentesis were 56% before the ACOG statement, 38% between the ACOG statement and NIPT introduction, and 10% after NIPT introduction (P=0.001). The rates of CVS during the same periods were 0.5%, 2.1%, and 4.3% (P=0.016), respectively. The rates of serum screening were 44.2%, 61.3%, and 55.1% (P=0.049), respectively. During the 3 quarters after NIPT introduction, the rates of amniocentesis were 16.2%, 12.3%, and 7.3% (P=0.002), respectively; the rates of serum screening were 62%, 54%, and 46% (P=0.03), respectively; and the rates of NIPT were 19.9%, 30.3%, and 39.5% (P=0.007), respectively. The rates of CVS over the same periods were not significantly different. CONCLUSION: The ACOG statement and NIPT introduction significantly decreased the rate of amniocentesis in women of advanced maternal age. NIPT also reduced the rate of serum screening.
Amniocentesis ; Aneuploidy ; Chorionic Villi Sampling ; Chromosome Aberrations* ; Diagnostic Tests, Routine ; Female ; Humans ; Mass Screening ; Maternal Age* ; Pregnancy ; Pregnancy, High-Risk ; Pregnant Women ; Prenatal Diagnosis ; Retrospective Studies

Objective: To evaluate the randomness and representativeness of respondent- driven sampling (RDS) tool in conducting the investigation in MSM population, in Beijing, 2017. Methods: RDS tool was used to recruit MSM population for a face-to-face interview with structured questionnaire and serological tests. Results: A total of 600 MSM people were sampled and interviewed. The median number of personal network of seeds was 10, which was higher than other MSM people recruited. The numbers of recruitments by wave presented a skewed positive distribution and the highest number was in the fourth wave. It was also dramatically varied from different seeds. Three seeds had the longest chains and had recruited 184, 113 and 92 MSM people, respectively. In contrast, five seeds recruited less than 10 MSM people. Two college students were the most non-generative seeds and each recruited only 1 MSM person. After five to nine waves of sampling, the major demographic characteristics reached equilibrium. Both convergence and bottleneck plots of major demographic characteristics reached convergence, although the plots on marriage and education did not. The homophiles of characteristics were all closed to 1, except for education. The HIV positive rate appeared as 7.9% (95%CI: 4.4%-11.4%) . Conclusions: Results from this study showed that RDS could be used as a feasible sampling method for the study on MSM population with major demographic characteristics reached equilibrium. The process of recruitment appeared controllable and reasonable, showing that this could represent the MSM population in Beijing, in some degree.
Beijing/epidemiology* ; HIV Infections/epidemiology* ; Homosexuality, Male/statistics & numerical data* ; Humans ; Male ; Outcome Assessment, Health Care/statistics & numerical data* ; Patient Selection ; Prevalence ; Sampling Studies ; Sexual and Gender Minorities ; Surveys and Questionnaires

PURPOSE: This study explored influencing factors on quality of life (QoL) above middle-aged women in relation to demographic factors, health-related factors, menopausal status, metabolic syndrome (MS) and its risk factors. METHODS: This study was secondary data analysis from the Sixth Korea National Health and Nutrition Examination Survey 2013~2015 that utilized a complex, multi-stage probability sample design. Study sample of 2,310 was inclusive of (28.8%) of women who were over 40. To evaluate the factors that would influence an impaired quality of life, χ² test, GLM, and logistic regression analysis were done. RESULTS: Level of quality of life was lower in women with late post-menopause(over 10 years since menopause) than women with pre-menopause. Factors influencing impaired QoL were as follows: graduated middle school and elementary school or less (OR=2.43, 4.42, respectively, p<.05), no job (OR=1.92, p<.001), stress (OR=1.92, p=.001), depression (OR=1.93, p=.001), insufficient sleep (OR=1.64, p=.003), late post-menopause (OR=2.61, p=.044) and over 85cm of waist circumference (OR=1.76, p=.01). CONCLUSION: These results suggest that late post-menopause may be an independent factor influencing an impaired QoL. To promote post-menopausal womens' health, a nursing strategy is required to teach women how to manage levels of stress, depression, insufficient sleep, and abdominal obesity through health education, nutritional counselling, and physical activity program.
Demography ; Depression ; Female ; Health Education ; Humans ; Korea ; Logistic Models ; Menopause ; Metabolic Syndrome X ; Motor Activity ; Nursing ; Nutrition Surveys ; Obesity, Abdominal ; Postmenopause ; Premenopause ; Quality of Life* ; Risk Factors* ; Sampling Studies ; Statistics as Topic ; Waist Circumference

OBJECTIVE: To validate quantitative fluorescent polymerase chain reaction (QF-PCR) via chorionic villus sampling (CVS) for the diagnosis of fetal aneuploidies. METHODS: We retrospectively reviewed the medical records of consecutive pregnant women who had undergone CVS at Cheil General Hospital between December 2009 and June 2014. Only cases with reported QF-PCR before long-term culture (LTC) for conventional cytogenetic analysis were included, and the results of these two methods were compared. RESULTS: A total of 383 pregnant women underwent QF-PCR and LTC via CVS during the study period and 403 CVS specimens were collected. The indications of CVS were as follows: abnormal first-trimester ultrasonographic findings, including increased fetal nuchal translucency (85.1%), advanced maternal age (6.8%), previous history of fetal anomalies (4.2%), and positive dual test results for trisomy 21 (3.9%). The results of QF-PCR via CVS were as follows: 76 (18.9%) cases were identified as trisomy 21 (36 cases), 18 (33 cases), or 13 (seven cases), and 4 (1.0%) cases were suspected to be mosaicism. All results of common autosomal trisomies by QF-PCR were consistent with those of LTC and there were no false-positive findings. Four cases suspected as mosaicism in QF-PCR were confirmed as non-mosaic trisomies of trisomy 21 (one case) or trisomy 18 (three cases) in LTC. CONCLUSION: QF-PCR via CVS has the advantage of rapid prenatal screening at an earlier stage of pregnancy for common chromosomal trisomies and thus can reduce the anxiety of parents. In particular, it can be helpful for pregnant women with increased fetal nuchal translucency or abnormal first-trimester ultrasonographic findings.
Aneuploidy* ; Anxiety ; Chorion* ; Chorionic Villi Sampling* ; Chorionic Villi* ; Cytogenetic Analysis ; Diagnosis ; Down Syndrome ; Female ; Fluorescence ; Hospitals, General ; Humans ; Maternal Age ; Medical Records ; Mosaicism ; Nuchal Translucency Measurement ; Parents ; Polymerase Chain Reaction* ; Pregnancy ; Pregnant Women ; Prenatal Diagnosis* ; Retrospective Studies ; Trisomy

OBJECTIVETo investigate the change pattern of primary and secondary school teachers' work ability with the changes in their mental workload.

METHODSA total of 901 primary and secondary school teachers were selected by random cluster sampling, and then their mental workload and work ability were assessed by National Aeronautics and Space Administration-Task Load Index (NASA-TLX) and Work Ability Index (WAI) questionnaires, whose reliability and validity had been tested. The effects of their mental workload on the work ability were analyzed.

RESULTSPrimary and secondary school teachers' work ability reached the highest level at a certain level of mental workload (55.73< mental workload ≤ 64.10). When their mental workload was lower than the level, their work ability had a positive correlation with the mental workload. Their work ability increased or maintained stable with the increasing mental workload. Moreover, the percentage of teachers with good work ability increased, while that of teachers with moderate work ability decreased. But when their mental workload was higher than the level, their work ability had a negative correlation with the mental workload. Their work ability significantly decreased with the increasing mental workload (P < 0.01). Furthermore, the percentage of teachers with good work ability decreased, while that of teachers with moderate work ability increased (P < 0.001).

CONCLUSIONToo high or low mental workload will result in the decline of primary and secondary school teachers' work ability. Moderate mental workload (55.73∼64.10) will benefit the maintaining and stabilization of their work ability.

Faculty ; statistics & numerical data ; Humans ; Occupational Health ; Reproducibility of Results ; Sampling Studies ; Schools ; Stress, Psychological ; psychology ; Surveys and Questionnaires ; Work ; psychology ; Workload ; psychology

OBJECTIVETo review the re-examination sampling method and procedure of national immunization survey for the national immunization program vaccines coverage at the township level by the national level in 2013, China.

METHODSAccording to the result of immunization coverage at the township level through self-assessment by county, all townships were stratified by whether a township with ≥ 90% immunization coverage for the second dose of measles-containing vaccines (MCV2), and a township was urban or rural. After then, 2 townships for each province were randomly sampled from those strata through the surveyselect procedure of the statistics analysis system 9.2 (SAS 9.2).

RESULTS64 townships were randomly sampled from 32 provincial units for the re-examination, i.e. an urban township and a rural township each province, of which there were 38 townships with ≥ 90% MCV2 coverage and 26 townships with < 90% MCV2 coverage. There were 24 urban townships, 2 rural townships with < 90% MCV2 coverage and 8 urban townships, 30 rural townships with ≥ 90% MCV2 coverage, respectively.

CONCLUSIONSBased on the information of the self-assessment result of immunization coverage survey by counties, Stratified randomized sampling were employed for the re-examination through the Surveyselect procedure of statistics analysis system (SAS) to implement the sampling procedure. This can enhance the sampling efficiency, ensure the randomness of the sample, and make the survey much more representative and comparable.

China ; Humans ; Immunization ; Immunization Programs ; statistics & numerical data ; Measles Vaccine ; Rural Population ; Sampling Studies ; Surveys and Questionnaires ; Urban Population ; Vaccination ; statistics & numerical data ; Vaccines