Prevalence of hypertensive disorders of pregnancy at or beyond 39 weeks gestational age and associated maternal complications

OBJECTIVE

Estimate the prevalence of hypertensive disorder of pregnancy (HDP) at term, define population characteristics, and calculate adverse maternal outcomes.

METHODS

Retrospective study.

RESULTS

We included 4,702,468 pregnancies. HDP increased linearly from 4.5% (2014) to 6.0% (2018). HDP was more frequent among black (PR 1.19), obese (PR 2.31 to 3.70), with gestational (PR 1.87) or pregestational diabetes (PR 2.16). Increased transfusion (PR 2.52), intensive care unit admission (PR 3.38), and unplanned hysterectomy (PR 1.78) with HDP.

CONCLUSION

Our study quantifies the increased risks for maternal and neonatal complications related to the development of HDP at or beyond 39 weeks among nulliparous women.

Anemia prevalence time trends and disparities in the US population: examination of NHANES 1999-2020

While a rising prevalence of anemia in the United States was reported in older studies, recent data are lacking. To estimate the prevalence and time trends of anemia in the United States and to examine how these estimates differ by gender, age, race, and household income to poverty threshold ratio (HIPR), we used the National Health and Nutrition Examination Surveys from 1999 to 2020. The presence of anemia was determined using the World Health Organization criteria. Survey-weighted raw and adjusted prevalence ratios (PRs) were determined using generalized linear models for the overall population and by gender, age, race, and HIPR. In addition, an interaction between gender and race was explored. Complete data on anemia, age, gender, and race were available on 87,554 participants (mean age = 34.6 years, women = 49.8%, Whites = 37.3%). Anemia prevalence increased from 4.03% during the 1999-2000 survey cycle to 6.49% during 2017-2020. In adjusted analyses, anemia prevalence was higher in >65 than in 26-45 years old (PR = 2.14, 95% confidence interval (CI) = 1.95, 2.35), in Blacks than Whites (PR = 3.97, 95% CI = 3.63, 4.35), in women than men (PR = 1.98, 95% CI = 1.83, 2.13), and in those with HIPR ≤ 1 than >4 (PR = 0.68, 95% CI = 0.61, 0.75). Gender modified the relationship between anemia and race; when compared to their male counterparts, Black, Hispanic, and other women had higher anemia prevalence than White women (all interaction p values <0.05). The anemia prevalence in the United States has risen from 1999 to 2020 and remains high among the elderly, minorities, and women. The difference in anemia prevalence between men and women is larger in non-Whites.

Regional differences in human papillomavirus type 52 prevalence among Japanese women with cervical intraepithelial neoplasia†

Although geographical differences in the distribution of human papillomavirus genotypes have been observed worldwide, no studies have reported on national differences in the prevalence of human papillomavirus types in Japan. Here, we report a cross-sectional study to explore regional differences in the prevalence of human papillomavirus types among Japanese women with cervical intraepithelial neoplasia or invasive cervical cancer. Using human papillomavirus genotyping data from the nationwide prospective study on human papillomavirus vaccine effectiveness, we compared the frequency of detection of 15 high-risk and two low-risk human papillomavirus types in each disease category between the women who visited hospitals located in eastern Japan and those who visited hospitals located in western Japan. The risk of cervical intraepithelial neoplasia progression was assessed by calculating a prevalence ratio of each human papillomavirus type for cervical intraepithelial neoplasia grade 2/3 versus grade 1. Among the human papillomavirus types studied, human papillomavirus 52 was detected significantly more frequently in western hospitals than in eastern hospitals in cervical intraepithelial neoplasia grade 1 patients, but was less frequent in cervical intraepithelial neoplasia grade 2/3. The prevalence of particular human papillomavirus types was not significantly different between patients in hospitals in eastern Japan and those in hospitals in western Japan for invasive cervical cancer. In both eastern and western hospitals, a higher risk of cervical intraepithelial neoplasia progression was observed in patients infected with human papillomavirus 16, 31 or 58. In contrast, there was a significantly higher prevalence of human papillomavirus 52 infection in women with cervical intraepithelial neoplasia grade 2/3 than in those with cervical intraepithelial neoplasia grade 1 in eastern hospitals (prevalence ratio, 1.93; 95% confidence interval, 1.48-2.58), but not in western hospitals (prevalence ratio, 1.03; 95% confidence interval, 0.83-1.30). Regional differences of human papillomavirus 52 prevalence in cervical intraepithelial neoplasia lesions may exist and emphasize the importance of continuous monitoring of human papillomavirus type prevalence throughout the country in order to accurately assess the efficacy of human papillomavirus vaccines.

Comorbidity in Older Patients Hospitalized with Cancer in Northeast China based on Hospital Discharge Data

Patients with cancer often carry the dual burden of the cancer itself and other co-existing medical conditions. The problems associated with comorbidities among elderly cancer patients are more prominent compared with younger patients. This study aimed to identify common cancer-related comorbidities in elderly patients through routinely collected hospital discharge data and to use association rules to analyze the prevalence and patterns of these comorbidities in elderly cancer patients at different cancer sites. We collected the discharge data of 80,574 patients who were diagnosed with cancers of the esophagus, stomach, colorectum, liver, lung, female breast, cervix, and thyroid between 2016 and 2018. The same number of non-cancer patients were randomly selected as the control group and matched with the case group by age and gender. The results showed that cardiovascular diseases, metabolic diseases, digestive diseases, and anemia were the most common comorbidities in elderly patients with cancer. The comorbidity patterns differed based on the cancer site. Elderly patients with liver cancer had the highest risk of comorbidities, followed by lung cancer, gastrointestinal cancer, thyroid cancer, and reproductive cancer. For example, elderly patients with liver cancer had the higher risk of the comorbid infectious and digestive diseases, whereas patients with lung cancer had the higher risk of the comorbid respiratory system diseases. The findings can assist clinicians in diagnosing comorbidities and contribute to the allocation of medical resources.

On the True Number of COVID-19 Infections: Effect of Sensitivity, Specificity and Number of Tests on Prevalence Ratio Estimation

In this paper, a formula for estimating the prevalence ratio of a disease in a population that is tested with imperfect tests is given. The formula is in terms of the fraction of positive test results and test parameters, i.e., probability of true positives (sensitivity) and the probability of true negatives (specificity). The motivation of this work arises in the context of the COVID-19 pandemic in which estimating the number of infected individuals depends on the sensitivity and specificity of the tests. In this context, it is shown that approximating the prevalence ratio by the ratio between the number of positive tests and the total number of tested individuals leads to dramatically high estimation errors, and thus, unadapted public health policies. The relevance of estimating the prevalence ratio using the formula presented in this work is that precision increases with the number of tests. Two conclusions are drawn from this work. First, in order to ensure that a reliable estimation is achieved with a finite number of tests, testing campaigns must be implemented with tests for which the sum of the sensitivity and the specificity is sufficiently different than one. Second, the key parameter for reducing the estimation error is the number of tests. For a large number of tests, as long as the sum of the sensitivity and specificity is different than one, the exact values of these parameters have very little impact on the estimation error.

Work Status, Financial Stress, Family Problems, and Gender Differences in the Prevalence of Depression in Chile

INTRODUCTION

It is widely known that women have a higher prevalence of depression than men. These differences may be explained by social differences between women and men due to gender roles. In Chile, as elsewhere, women have greater household responsibilities, lower job incomes, and especially low labor market participation. However, the incidence of these gender differences on the higher prevalence of depression in women requires further study in the Chilean context.

OBJECTIVE

To identify main social differences between women and men associated with gender differences in the prevalence of depression in middle-aged Chilean men and women.

DATA SOURCE

Data comes from the second Chilean National Health Survey (2009-2010), a cross-sectional, nationally representative sample (n = 2771) composed of 1103 men and 1668 women (39.8 and 60.2%, respectively), whose age range goes from 25 to 55 years old. This study was approved by the Ethics Committee of Pontificia Universidad Católica de Chile.

METHODS

Prevalence ratios were calculated through Poisson regression models to estimate associations between the prevalence of past episodes of depression and social stressful life events variables for men and women separately. Gender prevalence ratios of depression (Gender PR) adjusted for age and subsequently adjusted by the social and stressful life events variables. The analyses considered factors such as age, educational level, per-capita household income, work status, role as the head of household, marital status, events of violence, family problems, personal health problems or accidents, and self-reported financial stress.

RESULTS

This study finds that doing housework, reporting a serious family problem and having high financial stress were associated with a higher prevalence of depression in both genders. Whereas, health problems were only associated with prevalence in men. The age-adjusted gender PR was 2.84 [confidence interval (CI): 2.0-4.1], and when all selected variables were included attenuated to a PR of 1.86 (CI 1.3-2.7). The variable most strongly associated with depression in the fully-adjusted model was housework (PR: 5.3; CI: 1.3-21.0).

CONCLUSION

In conclusion, this study finds that depression in in Chile is associated with social factors such as participation in housework, family problems, and financial stress, all of which are more common in women. To make further progress in the study of this public health problem in Chile, it is essential to incorporate more detailed characterization of gender roles in surveys and other studies. Likewise, social policies and interventions that contribute to reduce gender social inequalities in the exposure to adverse life circumstances can contribute to reduce unnecessary and avoidable gender disparities in health.

Risk of olfactory dysfunction of the workers in the automobile repair, printing, shoemaking and plating industries in Korea: a cross-sectional study

OBJECTIVES

The present study was performed to investigate the prevalence of olfactory dysfunction in workers exposed to hazardous substances in a variety of occupations in Korea.

METHODS

We designed a cross-sectional study. The exposed group (n=296) consisted of Korean workers in the automobile repair, printing, shoemaking and plating industries and was compared with office workers (non-exposed group, n=99). A self-report questionnaire was administered to the subjects for demographic characteristics. In addition, olfactory function was evaluated using the Korean version of Sniffin's Stick (KVSS) I and II test, which has been reported to be valid and reliable in Korean subjects. KVSS I score ≥7 or KVSS II score ≥30 was classified as normal, KVSS I score <7 or KVSS II score <30 was classified as oflactory dysfunction. The statistical analyses were performed with olfactory dysfunction as a dependent variable to calculate prevalence ratio (PR) of the exposed group.

RESULTS

The prevalence of olfactory dysfunction was 21.2% in office, 45.1% in automobile repair, 69.7% in printing and 88.9% in shoemaking and plating workers. The adjusted PR was highest in plating (3.589, 95% CI 1.957 to 6.583), followed by shoemaking (3.136, 95% CI 1.763 to 5.579), printing (2.669, 95% CI 1.610 to 4.424) and automobile repair (1.914, 95% CI 1.105 to 3.317) workers.

CONCLUSIONS

In comparison with office workers, the prevalence of olfactory dysfunction and the PR of olfactory dysfunction were very high in the four occupational groups. This finding could be an important basis for establishing the olfactory dysfunction prevention policy for workers who are exposed to hazardous substances or work in high-risk occupations.

Odds Ratio or Prevalence Ratio? An Overview of Reported Statistical Methods and Appropriateness of Interpretations in Cross-sectional Studies with Dichotomous Outcomes in Veterinary Medicine

One of the most commonly observational study designs employed in veterinary is the cross-sectional study with binary outcomes. To measure an association with exposure, the use of prevalence ratios (PR) or odds ratios (OR) are possible. In human epidemiology, much has been discussed about the use of the OR exclusively for case–control studies and some authors reported that there is no good justification for fitting logistic regression when the prevalence of the disease is high, in which OR overestimate the PR. Nonetheless, interpretation of OR is difficult since confusing between risk and odds can lead to incorrect quantitative interpretation of data such as “the risk is X times greater,” commonly reported in studies that use OR. The aims of this study were (1) to review articles with cross-sectional designs to assess the statistical method used and the appropriateness of the interpretation of the estimated measure of association and (2) to illustrate the use of alternative statistical methods that estimate PR directly. An overview of statistical methods and its interpretation using the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines was conducted and included a diverse set of peer-reviewed journals among the veterinary science field using PubMed as the search engine. From each article, the statistical method used and the appropriateness of the interpretation of the estimated measure of association were registered. Additionally, four alternative models for logistic regression that estimate directly PR were tested using our own dataset from a cross-sectional study on bovine viral diarrhea virus. The initial search strategy found 62 articles, in which 6 articles were excluded and therefore 56 studies were used for the overall analysis. The review showed that independent of the level of prevalence reported, 96% of articles employed logistic regression, thus estimating the OR. Results of the multivariate models indicated that logistic regression was the method that most overestimated the PR. The findings of this study indicate that although there are methods that directly estimate PR, many studies in veterinary science do not use these methods and misinterpret the OR estimated by the logistic regression.

Geographic variation in psychotropic drug utilisation among older people in New Zealand

AIM

To examine psychotropic drug utilisation in older people in New Zealand by age, sex, health board domicile and deprivation status.

METHODS

A repeated cross-sectional analysis of population-based drug utilisation data stratified by age, sex, ethnicity, health board and deprivation status was conducted from 2005 to 2013.

RESULTS

Psychotropic utilisation increased between 2005 and 2013 (ranging from 7.0 to 74.0%) across all the health boards. In people aged 85 years and above, the hypnotic and sedative prevalence ratio compared to the 65- to 69-year age group was 1.45 (95% CI 1.44, 1.46). Between 2005 and 2013, the antidepressants prevalence ratio increased (1.27 (95% CI 1.22, 1.33)) relative to anxiolytics.

CONCLUSIONS

Overall psychotropic drug utilisation increased over time. Despite safety concerns, hypnotic and sedative utilisation increased in the oldest vulnerable group. Shifts from anxiolytics to antidepressants in some health boards were consistent with guidelines for extended indications of antidepressant drug use.

Exact inference for the risk ratio with an imperfect diagnostic test

The risk ratio quantifies the risk of disease in a study population relative to a reference population. Standard methods of estimation and testing assume a perfect diagnostic test having sensitivity and specificity of 100%. However, this assumption typically does not hold, and this may invalidate naive estimation and testing for the risk ratio. We propose procedures that control for sensitivity and specificity of the diagnostic test, given the risks are measured by proportions, as it is in cross-sectional studies or studies with fixed follow-up times. These procedures provide an exact unconditional test and confidence interval for the true risk ratio. The methods also cover the case when sensitivity and specificity differ in the two groups (differential misclassification). The resulting test and confidence interval may be useful in epidemiological studies as well as in clinical and vaccine trials. We illustrate the method with real-life examples which demonstrate that ignoring sensitivity and specificity of the diagnostic test may lead to considerable bias in the estimated risk ratio.

Prevalence odds ratio versus prevalence ratio: choice comes with consequences

Odds ratio, risk ratio, and prevalence ratio are some of the measures of association which are often reported in research studies quantifying the relationship between an independent variable and the outcome of interest. There has been much debate on the issue of which measure is appropriate to report depending on the study design. However, the literature on selecting a particular category of the outcome to be modeled and/or change in reference group for categorical independent variables and the effect on statistical significance, although known, is scantly discussed nor published with examples. In this article, we provide an example of a cross-sectional study wherein prevalence ratio was chosen over (Prevalence) odds ratio and demonstrate the analytic implications of the choice of category to be modeled and choice of reference level for independent variables. Copyright © 2016 John Wiley & Sons, Ltd.

Inverse association between altitude and obesity: A prevalence study among andean and low-altitude adult individuals of Peru

OBJECTIVE

To determine the association between altitude and obesity in a nationally representative sample of the Peruvian adult population.

METHODS

This is a cross-sectional analysis of publicly available data from the Food and Nutrition National Center (CENAN, Peru), period 2009-2010. The Prevalence ratio of obesity and abdominal obesity was determined as a measure of association. Obesity and abdominal obesity were diagnosed based on direct anthropometric measurements.

RESULTS

The final data set consisted of 31,549 individuals ≥20 years old. The prevalence ratio of obesity was as follows: 1.00 between 0 and 499 m (reference category), 1.00 (95% confidence interval 0.87-1.16) between 500-1,499 m, 0.74 (0.63-0.86) between 1,500-2,999 m, and 0.54 (0.45-0.64) at ≥3,000 m, adjusting for age, sex, self-reported physical activity, out-migration rate, urbanization, poverty, education, and geographical latitude and longitude. In the same order, the adjusted prevalence ratio of abdominal obesity was 1.00, 1.01 (0.94-1.07), 0.93 (0.87-0.99), and 0.89 (0.82-0.95), respectively. We found an interaction between altitude and sex and between altitude and age (P < 0.001, for both interactions) on the association with obesity and abdominal obesity.

CONCLUSIONS

Among Peruvian adult individuals, we found an inverse association between altitude and obesity, adjusting for multiple covariates. This adjusted association varied by sex and age.

Human papillomavirus genotype distribution in cervical intraepithelial neoplasia grade 2/3 and invasive cervical cancer in Japanese women

OBJECTIVE

Human papillomavirus vaccines are being introduced worldwide and are expected to reduce the incidence of cervical cancer. Here we report a cross-sectional study using a validated human papillomavirus genotyping method to reveal the human papillomavirus prevalence and genotype distribution in Japanese women with cervical intraepithelial neoplasia Grade 2/3 and invasive cervical cancer.

METHODS

Cervical exfoliated cells were collected from 647 patients with abnormal cervical histology (cervical intraepithelial neoplasia Grade 2, n = 164; cervical intraepithelial neoplasia Grade 3, n = 334; and invasive cervical cancer, n = 149), and subjected to the PGMY-PCR-based genotyping assay. The association between human papillomavirus infection and lesion severity was calculated using a prevalence ratio.

RESULTS

Overall, the prevalence of human papillomavirus deoxyribonucleic acid was 96.3% in cervical intraepithelial neoplasia Grade 2, 98.8% in cervical intraepithelial neoplasia Grade 3 and 88.0% in invasive cervical cancer (97.8% in squamous cell carcinoma and 71.4% in adenocarcinoma). The three most prevalent types were as follows: human papillomavirus 16 (29.3%), human papillomavirus 52 (27.4%) and human papillomavirus 58 (22.0%) in cervical intraepithelial neoplasia Grade 2; human papillomavirus 16 (44.9%), human papillomavirus 52 (26.0%) and human papillomavirus 58 (17.4%) in cervical intraepithelial neoplasia Grade 3; and human papillomavirus 16 (47.7%), human papillomavirus 18 (23.5%) and human papillomavirus 52 (8.7%) in invasive cervical cancer. The prevalence ratio of human papillomavirus 16 was significantly higher in cervical intraepithelial neoplasia Grade 3 compared with cervical intraepithelial neoplasia Grade 2 (prevalence ratio, 1.62; 95% confidence interval, 1.26-2.13) and in squamous cell carcinoma compared with cervical intraepithelial neoplasia Grade 3 (prevalence ratio, 1.55; 95% confidence interval, 1.25-1.87). Multiple infections decreased from cervical intraepithelial neoplasia Grade 2/3 (38.4/29.6%) to invasive cervical cancer (14.1%), whereas co-infections with human papillomavirus 16/52/58 were found in cervical intraepithelial neoplasia Grade 2/3.

CONCLUSIONS

The results of this study provide pre-vaccination era baseline data on human papillomavirus type distribution in Japanese women and serve as a reliable basis for monitoring the future impact of human papillomavirus vaccination in Japan.

Factors associated with genital human papillomavirus infection among adult females in the United States, NHANES 2007-2010

BACKGROUND

Patients with human papillomavirus (HPV) infection are at risk of developing cancer later in their life. Current research estimates the prevalence of genital HPV infection and explores the factors that are associated with the infection.

FINDINGS

The National Health and Nutrition Examination Survey 2007-2010 was used in this research study. The study population included females in the United States aged 18-59 years. The weighted prevalence of HPV infection was 41.9%. An estimated 59.4% of non-Hispanic black females had HPV infection. In a multivariate analysis, number of sexual partners, race, age, education level, marital status, income, smoking, and insurance status were associated with HPV infection. HPV infection was 5.77 times more likely for women with >11 sexual partners compared to women with 0-1 partners. Non-Hispanic black females were 1.87 times more likely to have HPV infection compared to non-Hispanic white females. Participants with only a high school degree had a 58% increased prevalence compared to college-educated women. Uninsured women had a 39% increased prevalence compared to those with insurance.

CONCLUSION

This study found that 41.9% of U.S. females aged 18-59 years tested positive for genital HPV infection. We determined that individuals with more sexual partners, with a lower education level, with non-Hispanic black race, and with no insurance were the populations at greatest risk. It is necessary to continue monitoring the prevalence of this infection in the general population to provide a basis for effective treatment and prevention in the target populations.

Serotype distribution and antimicrobial susceptibilities of nasopharyngeal isolates of Streptococcus pneumoniae from healthy children in the 13-valent pneumococcal conjugate vaccine era

Few epidemiological data are available since the introduction of 13-valent pneumococcal vaccine (PCV13) in 2010. We conducted a cross-sectional study to estimate the prevalence of Streptococcus pneumoniae (SP) nasopharyngeal carriage in healthy Italian infants and young children and to evaluate the impact of PCV13 on pneumococcal colonization. In the trimester September-December 2011 nasopharyngeal swabs were collected from healthy children aged 3-59 months presenting for routine well careat 16 primary care pediatricians in Milan. SP carriage isolates were serotyped and tested for antimicrobial resistance using EUCAST breakpoints. Among 1250 enrolled children, 618 had received at least 1 dose of PCV13, 292 at least 1 dose of PCV7, 94 a combination of the two vaccines and 246 were not vaccinated. The prevalence of SP carriage was 27% (95% confidence interval [CI] 25-30). At multivariable analysis, age≥25 months (prevalence ratio [PR]=0.74) and use of antibiotics in the previous 3 months (PR=0.67) were associated with lower SP carriage prevalence. Having siblings (PR=1.79 for 1 sibling and PR=2.23 for ≥2 siblings), day-care attendance (PR=2.27) and respiratory tract infections in the previous 3 months (PR=1.39) were associated with higher SP carriage prevalence. The immunization status for SP was not associated with SP carriage at univariable or at multivariable analysis. The most common carriage isolates were 6C, 19A and 23A. The prevalence of the six additional PCV13 serotypes carriage in children appropriately vaccinated with PCV13 was lower than in children appropriately vaccinated with PCV7 (0 vs. 0.060); the greater reduction in prevalence of carriage was observed for serotype 19A (0 vs. 0.041). Serotype 6C was the most common drug-resistant serotype (17.2%). Further epidemiological studies are needed to assess changes in circulating SP serotypes following the large-scale introduction of PCV13.

Risk factors for fractures among Japanese-American men: The Honolulu Heart Program and Honolulu-Asia Aging Study

Baseline risk factors were associated with fractures that developed after 29-31 years among Japanese-American men. Hip fracture risk increased with increasing BMI (28% increase for 1 U increase), physical activity (7% increase for 1 U increase), and was decreased with increasing arm girth (27% decrease for 1 U increase).

PURPOSE

The objective of this study was to identify risk factors among Japanese-American men aged 45-68 years at baseline that were associated with prevalence and incidence of fractures at advanced age.

METHODS

We used baseline information from Honolulu Heart Program (HHP) and Honolulu-Asia Aging Study (HAAS). The HHP was a prospective study with primary focus on risk factors for cardiovascular disease. A cohort of 8,006 men of Japanese ancestry aged 45-68 years residing on Oahu was recruited in 1965 and followed for 31 years. The HAAS started in 1991 in conjunction with the HHP with a focus on age-related health conditions. Self-reported hip, spine, and forearm fracture prevalence was ascertained in 1991-1993 among 3,845 men aged 71-93 years. Incidence was obtained during the period (1994-1999) among 2,737 men aged 74-98 years. Poisson regression models were used to determine multi-variable adjusted prevalence and incidence ratios for fracture.

RESULTS

Incident hip fracture was directly associated with baseline body mass index (BMI) and physical activity, and inversely associated with left upper arm girth. Incident spine fracture was directly associated with baseline age. Prevalent hip fracture was directly associated with baseline pack-years of smoking. Prevalent spine fracture was inversely associated with baseline education, and directly associated with standing height and use of medication for diabetes. Prevalent forearm fracture was inversely associated with baseline age, and directly associated with education.

CONCLUSIONS

Results indicated that multiple baseline demographic lifestyle and anthropometric characteristics predict fracture risk at advanced age. In addition, associations varied by fracture location.

Estimating relative risks for common outcome using PROC NLP

In cross-sectional or cohort studies with binary outcomes, it is biologically interpretable and of interest to estimate the relative risk or prevalence ratio, especially when the response rates are not rare. Several methods have been used to estimate the relative risk, among which the log-binomial models yield the maximum likelihood estimate (MLE) of the parameters. Because of restrictions on the parameter space, the log-binomial models often run into convergence problems. Some remedies, e.g., the Poisson and Cox regressions, have been proposed. However, these methods may give out-of-bound predicted response probabilities. In this paper, a new computation method using the SAS Nonlinear Programming (NLP) procedure is proposed to find the MLEs. The proposed NLP method was compared to the COPY method, a modified method to fit the log-binomial model. Issues in the implementation are discussed. For illustration, both methods were applied to data on the prevalence of microalbuminuria (micro-protein leakage into urine) for kidney disease patients from the Diabetes Control and Complications Trial. The sample SAS macro for calculating relative risk is provided in the appendix.