Biomedical subjects

Ruiguang Song

Publications and source records attributed to Ruiguang Song.

9 recordsLinked to original sources

PubMed2006

Assessing the completeness of reporting of human immunodeficiency virus diagnoses in 2002-2003: capture-recapture methods.

To determine the completeness of reporting of human immunodeficiency virus (HIV) diagnoses to state surveillance systems, the authors used capture-recapture methods. The numbers of cases diagnosed in the areas were estimated using HIV diagnoses reported to nine surveillance programs by different sources (e.g., laboratories, health-care providers). To account for dependencies between reporting sources, the authors used log-linear models to estimate the number of cases that had been diagnosed but were not identified by any reporting sources. Completeness of reporting (observed cases/expected cases) was determined for two time frames: cases diagnosed within a 1-year period (from October 1, 2002, to September 30, 2003, for most US states) reported up to 6 months after that diagnosis period and cases diagnosed within a 6-month period reported up to 12 months after that diagnosis period. A total of 11,266 HIV diagnoses were reported for the 1-year period with 21,589 report documents. Completeness of reporting of HIV diagnoses was 76% (95% confidence interval: 66, 83) when allowing 6 months of reporting delay (range: 72-95%) and improved to 81% (95% confidence interval: 72, 88) with 12 months' follow-up. When reporting systems retain all relevant documents, capture-recapture is a feasible approach for assessing completeness of reporting of HIV diagnoses. Completeness should be measured by allowing 12-months' reporting delay.

Data Collection↗

PubMed2006

Estimating the distribution of a renewal process from times at which events from an independent process are detected.

The analysis of length-biased data has been mostly limited to the interarrival interval of a renewal process covering a specific time point. Motivated by a surveillance problem, we consider a more general situation where this time point is random and related to a specific event, for example, status change or onset of a disease. We also consider the problem when additional information is available on whether the event intervals (interarrival intervals covering the random event) end within or after a random time period (which we call a window period) following the random event. Under the assumptions that the occurrence rate of the random event is low and the renewal process is independent of the random event, we provide formulae for the estimation of the distribution of interarrival times based on the observed event intervals. Procedures for testing the required assumptions are also furnished. We apply our results to human immunodeficiency virus (HIV) test data from public test sites in Seattle, Washington, where the random event is HIV infection and the window period is from the onset of HIV infection to the time at which a less sensitive HIV test becomes positive. Results show that the estimator of the intertest interval length distribution from event intervals ending within the window period is less biased than the estimator from all event intervals; the latter estimator is affected by right truncation. Finally, we discuss possible applications to estimating HIV incidence and analyzing length-biased samples with right or left truncated data.

AIDS Serodiagnosis↗

PubMed2005

Discontinuation of primary prophylaxis against Mycobacterium avium complex infection in HIV-infected persons receiving antiretroviral therapy: observations from a large national cohort in the United States, 1992-2002.

In a large, diverse cohort of human immunodeficiency virus (HIV)-infected persons receiving routine care, the proportion of eligible persons who discontinued primary prophylaxis against Mycobacterium avium complex (MAC) infection, according to guidelines of the US Public Health Service and the Infectious Diseases Society of America, increased from 16.7% (in 1996) to 84.9% (in 2002). The discontinuation of primary prophylaxis was not associated with an increased risk of disseminated MAC infection.

AIDS-Related Opportunistic Infections↗

PubMed2005

Uncertainties associated with incidence estimates of HIV/AIDS diagnoses adjusted for reporting delay and risk redistribution.

Reporting delay occurs frequently in the case surveillance of a disease such as HIV/AIDS. To evaluate the current trend of incidence, it is important to consider incidence estimates adjusted for reporting delays and the uncertainty associated with this adjustment. For a surveillance system in which cases are reported monthly, there is no straightforward method for constructing the confidence interval estimators for annual incidence or incidence for a period longer than a month. This is because the monthly incidence estimators are not independent and the correlations among them are not available. Furthermore, to estimate the incidence for a specific risk, or exposure, group (e.g. men who have sex with men), we also have to consider the uncertainty associated with the counts from cases reported without an identified risk. Cases with no reported risk are assigned proportionally to each risk group on the basis of experience with cases reported initially with no reported risk but reported later with an identified risk. In this article, we introduce a method for combining the uncertainties associated with both reporting delay and risk redistribution. An estimator for the covariance between two incidence estimators is also provided so that we can make pairwise comparisons and discover any significant changes in incidence over time. Results are applied to evaluating the current trends in AIDS incidence among men who have sex with men in the United States.

Acquired Immunodeficiency Syndrome↗

PubMed2005

Describing the HIV/AIDS epidemic: using HIV case data in addition to AIDS case reporting.

PURPOSE: We examined the demographic and risk characteristics of persons with HIV using traditional AIDS case reporting and the more recent system that includes HIV diagnoses without AIDS. METHODS: Using data from 25 states with HIV reporting of HIV/AIDS cases diagnosed from 1994 through 2001, we calculated percentage distributions, annual diagnosis rates, and estimated annual percent change (EAPC) for persons with HIV (all HIV diagnoses with or without AIDS) and persons with AIDS. RESULTS: The age at diagnosis of persons with all stages of HIV tended to be younger than that of the subset of persons with AIDS. Annual diagnosis rates decreased more among AIDS cases (men: EAPC, - 9.76; 95% CI, - 12.00, - 7.45; women: EAPC, - 3.40; 95% CI - 5.72, - 1.02) than for persons with HIV (men: EAPC, - 6.14; 95% CI, - 7.66, - 4.60; women: EAPC, - 2.99; 95% CI, - 4.15, - 1.82), except among women and black non-Hispanics, for whom the difference in the decreases in rates for both disease groups were small. Injection drug use was a more common mode of exposure for women with AIDS than for women with HIV. CONCLUSIONS: The epidemiology of HIV differs for certain key population groups from that of AIDS.

Acquired Immunodeficiency Syndrome↗

PubMed2005

Association of CCR5 human haplogroup E with rapid HIV type 1 disease progression.

The combination of unique single nucleotide polymorphisms in the CCR5 regulatory and in the CCR2 and CCR5 coding regions, defined nine CCR5 human haplogroups (HH): HHA-HHE, HHF*1, HHF*2, HHG*1, and HHG*2. Here we examined the distribution of CCR5 HH and their association with HIV infection and disease progression in 36 HIV-seronegative and 76 HIV-seropositive whites from North America and Spain [28 rapid progressors (RP) and 48 slow progressors (SP)]. Although analyses revealed that HHE frequencies were similar between HIV-seronegative and HIV-seropositive groups (25.0% vs. 32.2%, p > 0.05), HHE frequency in RP was significantly higher than that in SP (48.2% vs. 22.9%, p = 0.002). Survival analysis also showed that HHE heterozygous and homozygous were associated with an accelerated CD4 cell count decline to less than 200 cells/microL (adjusted RH 2.44, p = 0.045; adjusted RH = 3.12, p = 0.037, respectively). These data provide further evidence that CCR5 human haplogroups influence HIV-1 disease progression in HIV-infected persons.

Acquired Immunodeficiency Syndrome↗

PubMed2005

Epidemiology of HIV/AIDS among Asians and Pacific Islanders in the United States.

Although the percentage of overall AIDS diagnoses remains low among Asian and Pacific Islanders (APIs) in the United States compared with other racial/ethnic groups, research on API risk behaviors and health status suggest that the low number of AIDS cases may not provide a full picture of the epidemic and issues faced by this understudied and underserved population. Data from national HIV/AIDS surveillance systems and the Behavioral Risk Factor Surveillance System (BRFSS) were examined to delineate the magnitude and course of the HIV/AIDS epidemic among APIs in the United States. Same-sex sexual activity is the main HIV risk for API men, whereas heterosexual contact is for API women. APIs are significantly less likely to report being tested for HIV despite the fact that a similar proportion of APIs and other racial/ethnic groups reported having HIV risk in the past 12 months. Given the enormous diversity among APIs in the United States it is important to collect detailed demographic information to improve race/ethnicity and HIV risk classification, conduct better behavioral and disease monitoring for informing prevention planning, and addressing cultural, linguistic, economic and legal barriers to HIV prevention among APIs.

Acquired Immunodeficiency Syndrome↗

PubMed2003

Evaluation of two portable lead-monitoring methods at mining sites.

Two methods for measuring airborne lead using field-portable instruments have been developed by the National Institute for Occupational Safety and Health (NIOSH): Method 7702 uses X-ray fluorescence (XRF), and Method 7701 employs ultrasonic extraction (UE) followed by anodic stripping voltammetry (ASV). The two portable methods were evaluated at mining sites. Area air samples were collected throughout two mills where ore from nearby mines was processed; the primary constituent of the ore was lead sulfide (galena). The air samples were collected on 37 mm mixed cellulose ester membrane filters housed within plastic filter cassettes. At the end of the work shift, the cassettes were collected and taken to a room off-site for analysis by the two portable methods. The filter samples were first analyzed by XRF and then by UE/ASV. Calibration was verified on both instruments according to standard procedures. The samples were then sent for confirmatory analysis via flame atomic absorption spectrometry (FAAS) according to NIOSH Method 7082. Pairwise comparisons between the methods using the paired t-test showed no statistically significant differences between ASV and FAAS (P>0.05); however, the comparison between XRF and FAAS was statistically significant (P<0.05). The elevated lead concentrations reported by XRF relative to FAAS were likely the result of the ability of XRF to report total lead, including lead silicates. This form of lead is not liberated in the digestion process prior to FAAS analysis, and is therefore not detected by this method. Despite this discrepancy, lead concentrations measured by both portable technologies were found to be highly correlated with the laboratory method (R2>0.96), suggesting that they are suitable as screening methods for airborne lead at mining sites.

Air Pollutants↗

PubMedDate not supplied

Frequency distributions from birth, death, and creation processes.

The time-dependent frequency distribution of groups of individuals versus group size was investigated within a continuum approximation, assuming a simplified individual growth, death and creation model. The analogy of the system to a physical fluid exhibiting both convection and diffusion was exploited in obtaining various solutions to the distribution equation. A general solution was approximated through the application of a Green's function. More specific exact solutions were also found to be useful. The solutions were continually checked against the continuum approximation through extensive simulation of the discrete system. Over limited ranges of group size, the frequency distributions were shown to closely exhibit a power-law dependence on group size, as found in many realizations of this type of system, ranging from colonies of mutated bacteria to the distribution of surnames in a given population. As an example, the modeled distributions were successfully fit to the distribution of surnames in several countries by adjusting the parameters specifying growth, death and creation rates.

Death↗