Estimation of Seasonal Quality-Adjusted Life-Year Using Seemingly Unrelated Regression Equation Models With an Application to Orthopedic Data.

OBJECTIVES: The technological advancement in the field of orthopedics has initiated better healthcare service that equates to the need of cost-effectiveness approach. We propose a model for estimating the simultaneous effect of health and cost involved in an orthopedic surgery implants by using seemingly unrelated regression equations models. METHODS: The simultaneous equations represent a relationship between the health status of a group of individuals and their expenditures related to the cost of surgical procedure/treatment undertaken in an orthopedic department of a hospital. We define model specification, estimation, and statistical tests in simultaneous equation models. This is further used to estimate the utility function that indeed helps in the computation of quality-adjusted life-year (QALY) values. RESULTS: Using the seemingly unrelated regression equation models for the seasonal data in 2018 and 2019, we have obtained the seasonal QALY values. Furthermore, the measurement of seasonal changes in QALY values is done by using a method of simple averages. CONCLUSIONS: We analyze the health conditions in orthopedics by the formation of health and expenditure relationship for the inpatients and outpatients undertaking a treatment. A framework has been setup for computing quality of life-year values by including the direct and the indirect costs. The patient-reported outcome measures are also useful in detecting the change in disease states and important difference in minimal clinical changes that further adds value to the computation of quality of life.

A new extension of state-space SIR model to account for Underreporting - An application to the COVID-19 transmission in California and Florida.

In the absence of sufficient testing capacity for COVID-19, a substantial number of infecteds are expected to remain undetected. Since the undetected cases are not quarantined, they can be expected to transmit the infection at a much higher rate than their quarantined counterparts. That is, in the absence of extensive random testing, the actual prevalence and incidence of the SARS-CoV-2 infection can be significantly higher than that being reported. Thus, it is imperative that the information on the percentage of undetected (or unreported) cases be incorporated in the mechanism for estimating the key epidemiological parameters, like rate of transmission, rate of recovery, reproduction rate, etc., and hence, for forecasting the transmission dynamics of the epidemic. In this paper, we have developed a new dynamic version of the basic susceptible-infected-removed (SIR) compartmental model, called the susceptible-infected (quarantined/ free) - recovered- deceased [SI(Q/F)RD] model, to assimilate the impact of the time-varying proportion of undetected cases on the transmission dynamics of the epidemic. Further, we have presented a Dirichlet-Beta state-space formulation of the SI(Q/F)RD model for the estimation of its parameters using posterior realizations from the Gibbs sampling procedure. As a demonstration, the proposed methodology has been implemented to forecast the COVID-19 transmission in California and Florida. Results suggest significant amount of underreporting of cases in both states. Further, posterior estimates obtained from the state-space SI(Q/F)RD model show that average reproduction numbers associated with the undetected infectives [California: 1.464; Florida: 1.612] are substantially higher than those associated with the quarantined infectives [California: 0.497; Florida: 0.359]. The long-term forecasts of death counts show trends similar to those of the estimates of excess deaths for the comparison period post training data timeline.

A Study Comparing Cost-Effectiveness of Combination Therapy for Preventing Opportunistic Infections Among Human Immunodeficiency Virus-Infected Adults on Antiretroviral Therapy.

OBJECTIVES: India is going through an epidemiologic and demographic transition made possible by increased investment in health sector and sustained development. The country has more than 2 million people infected with human immunodeficiency virus (HIV). Information on cost-effectiveness of competing interventions is a useful contributor to decisions concerning allocation and prioritization of healthcare resources. This paper aims to study the cost, health outcomes as measured by disability-adjusted life-years (DALYs), and cost-effectiveness per DALY averted of prophylaxis for tuberculosis, diarrhea, and mouth ulcers in HIV-infected adults. METHODS: Data were analyzed on 375 HIV-infected persons enrolled at the ART Centre in New Delhi between April 2004 and April 2006. Using estimates of the age of onset of HIV infection, cost of medicines, and antiretroviral regimen followed, we used standard methods to calculate the cost per DALY as a measure of cost-effectiveness. Sensitivity analysis was conducted to determine the robustness of cost-effectiveness results by making reasonable changes in underlying assumptions. RESULTS: The results revealed that the incremental cost-effectiveness ratio for tuberculosis prophylaxis was ₹4821.48 ($78.86) per DALY averted compared with no prophylaxis, followed by diarrhea (₹8299.08, $135.74) and mouth ulcers (₹20 058.14, $328.07). CONCLUSIONS: The estimates are less than the per capita gross domestic product of India, indicating that the current treatments are highly cost-effective. This will help policymakers understand the best opportunities to improve population health and help researchers to develop more standardized methods in the area, thus improving quality and comparability across cost per DALY studies.

Modelling and forecasting Positive and Negative Syndrome Scale scores to achieve remission using time series analysis.

OBJECTIVES: Schizophrenia is a chronic mental condition. The objective of this study is to apply time series modelling to Positive and Negative Syndrome Scale scores of outpatients with schizophrenia, observed at regular intervals of time, and hence forecast the number of visits required to reach remission. METHODS: A retrospective data of outpatients diagnosed with chronic paranoid-type schizophrenia were extracted from the records of outpatient department of a tertiary hospital in New Delhi, India. Autoregressive integrated moving average (ARIMA) and ARIMAX models (ARIMA with explanatory variable as Clinical Global Impression Severity scale) are fitted to the data. The best fit models are employed to forecast the number of visits required to reach remission for the outpatients who did not achieve remission by the end of study. Prediction accuracy of the two models is compared using mean absolute percentage error and mean absolute deviation. RESULTS: The ARIMA (1, 2, 1) and ARIMAX (1, 2, 1) models are identified to be suitable models after a series of statistical tests. CONCLUSIONS: ARIMA and ARIMAX models are suitable to predict number of visits required to reach remission. Further, ARIMAX model performed better than ARIMA model.

On the estimation of survival and death probabilities under myocardial infarctions in the presence of competing risks based on an illness-death model.

This paper is concerned with the development of an illness-death model for the study of survivability of heart patients. The Myocardial Infarctions (MI) experienced in heart disease have been categorized as fatal and nonfatal. Fatal MI's are easily recognizable and identified and are always reported in the case history of the patient suffering from heart disease whereas non-fatal MI's are not easily identified and are rarely reported in the case history of the patient. Also, in the case of human population, all individuals are not equally healthy and the chance of dying varies from one person to another. Moreover illness and death are two different types of events. Illness may be transient, repetitive and reversible, whereas death is an irreversible or absorbing state. Further complexity is introduced by competition among various risks of death. The probability of an individual dying from one cause is influenced by the presence of competition from other causes. Here in our problem we have taken two health states viz. normal state and illness state due to non-fatal MI's, and two death states viz. death state due to fatal MI and death state due to competing risk. The study population of n individuals is divided into two groups viz. n1 individuals who are in the normal state and n2 individuals who are in the illness state due to non-fatal MI's, at the time of start of the study. The expressions for survival and death probabilities have been obtained by using the concep of crude probability of death under competing risks. The likelihood estimates of the survival and death probabilities have also been obtained. Application of the model is discussed.

A study of cardiovascular risk factors in Delhi, India.

Acute myocardial infarction (AMI) is a leading cause of mortality and disability of adults in urban and rural India, and occurs at younger age than in western populations. In this paper an attempt has been made to determine the risk factors for non- fatal AMI among Indian men and women and to study the difference in proportion of risk factors by taking non- AMI group along with healthy group as controls. Mantel Haenzel test showed that while comparing AMI with non-AMI group, diabetes mellitus (p < 0.05), family history of MI (p < 0.0001) and smoking (p < 0.0001) are significantly associated with AMI after adjusting the effects of hypertension. The same test was carried out in comparing AMI with healthy group which showed that diabetes mellitus (p < 0.05), family history of MI (p < 0.0001) and smoking (p < 0.0001) are significantly associated with AMI after adjusting the effects of hypertension. Similarly, while comparing CVD group with healthy group, family history of MI (p < 0.0001) and smoking (p < 0.0001) are significantly associated with CVD after adjusting the effects of hypertension. Stepwise logistic regression showed that while comparing AMI cases with non- AMI controls, arrhythmias (odds ratio (OR) = 5.196, p < 0.0001), angina (OR = 3.599, p < 0.0001), CHF (OR = 3.121, p < 0.0001), hypertension (OR = 2.717, p < 0.0001), smoking (OR = 1.993, p < 0.0001) and family history of MI (OR = 1.819, p < 0.01) were important risk factors for a first myocardial infarction. Moreover, while comparing AMI cases with healthy controls, family history of AMI (OR = 15.925, p < 0.0001), smoking (OR = 2.806, p < 0.001), hypertension (OR = 2.718, p < 0.0001), gender (OR = 2.410, p < 0.01) and age (OR = 2.410, p < 0.05) were important predictors of AMI; and while comparing CVD cases (AMI and non-AMI) with healthy group, family history of MI (OR = 10.377, p < 0.01), hypertension (OR = 8.237, p < 0.01) and smoking (OR = 4.454, p < 0.01), were important predictors of cardiovascular disease.

Changing patterns of cardiovascular risk factors and heart related sickness in relation with acute myocardial infarction in Delhi, India.

In this article an attempt has been made to investigate the 10-year trend of cardiovascular risk factors and common heart related sickness including angina, arrhythmias and congestive heart failure, and to study the impact of cardiovascular risk factors and heart related sickness on time between two acute myocardial infarctions. Chi-square test showed that in comparison to two 5-year study periods, the proportion of smoking, arrhythmias and congestive heart failure increased significantly in the second 5-year study period and the proportion of hypertension decreased significantly in the second 5-year study period. Moreover, with regard to occurrence of myocardial infarction under the age of 45 years, the prevalence decreased significantly in the second 5-year period. Cox regression model with time dependent covariates showed that gender, hypercholesterolaemia, congestive heart failure and arrhythmias were found to be important predictors associated with reduced time to second episode of myocardial infarction. The purpose of this study will help the physicians to detect the risk factors associated with reduced time between two myocardial infarctions after the occurrence of first episode of myocardial infarction so that by controlling the risk factors will either increase the duration between two myocardial infarctions or prevent the occurrence of second episode and hence improving the survival time of the patients.

Behavioural disorders in 6-11-year-old, HIV-infected Indian children.

BACKGROUND: HIV-infected children are at risk of behaviour problems. The transition of HIV from an acute, lethal disease to survival with sub-acute, chronic disease has enormous implications for the psychosocial development and requirement for support of affected children and families. AIM: To study the behavioural patterns and factors responsible for psychiatric disorders among HIV-infected and uninfected children in the age group 6-11 years. METHODS: A prospective, random-sampling study was undertaken to examine the unique and combined influences of HIV and socio-demographic characteristics on the behaviour of 140 infected and 301 age- and income-matched controls. Controls were normal children recruited from government schools. The Child Behaviour Check List was used to assess behaviour patterns. RESULTS: Multivariate analyses comparing HIV-infected children with their uninfected peers from similar backgrounds showed more subjective distress in the HIV-infected group. Behaviour problems in HIV-infected children were reported by 80.7% of primary caregivers compared with 18.3% for controls. Psychiatric behaviour in HIV-infected children as a risk factor for HIV was also identified in a significant proportion (p<0.0001). CONCLUSIONS: By analysing behaviour, a psycho-medical team can examine the extent to which psychosocial and demographic factors are involved in causing and exacerbating behaviour problems in HIV-infected children.

Nonparametric estimation of survival function of HIV+ patients with doubly censored data.

In the analysis of follow-up studies of patients who have been or may be infected by the Type-1 human immunodeficiency virus (HIV-1), which causes the acquired immune deficiency syndrome (AIDS), one problem of interest is the estimation of distribution of the survival function when the origin and end points defining the survival time suffer interval censoring. In this paper, we have compared Kaplan-Meier, midpoint estimation and sun (1997), by analysis of a cohort study data of Iranian Injecting Drug Users (IDU) who became HIV infected through the using common infected syringe.

Role of HCV coinfection towards disease progression and survival in HIV-1 infected children: a follow-up study of 10 years.

The present study was taken up to evaluate the pattern of disease progression and survival in a group of HIV-1 positive children, coinfected with HCV infection (n=25) in comparison to those without such coinfection (n=23). There was a significant negative correlation between the rate of decline of the CD4 + T cell percentage and the duration of the AIDS-free interval in most (80.0 per cent) of the HCV seropositive children showing such decline (r=-0.588; p=0.005). The HCV seropositive children had twofold higher risk of progression to development of AIDS than HCV seronegatives (RR=2.51; 95 per cent CI:1.34-4.69; p=0.004). There was a significant negative correlation between the rate of decline of CD4 + T cell percentage and overall survival duration for HCV seropositive group (r=-0.609; p=0.003). Moreover, children coinfected with HCV had more than twofold higher risks of death than those without HCV (RR=2.39; 95 per cent CI:1.17-4.89; p<0.01). It appears that HCV infection may be an important contributor to the rapid disease progression and increase in mortality in HCV-HIV-1 coinfected children of thalassemia major.

On the construction of clinical life table for studying the survivability of diagnosed AIDS cases.

In this paper, an attempt has been made to estimate the various survival functions of clinically diagnosed AIDS cases by the life table method. The actuarial life table method has already been applied to clinical data for many decades. To exhibit computations for the clinical life table, we have used the clinical data gathered on diagnosed 731 male and female AIDS patients recorded from Dec.1993 up to Dec.2002 in Delhi. The method is also used to study the nature of the survival functions for the AIDS patients with different causes of death. The comparisons among various survival functions are shown with the help of the graphs.

Survival pattern of reported HIV infected individuals in the city of Delhi (India).

There is very little data on the survival period of HIV in India. In this paper survival experience of 836 HIV infected patients was studied whose illness was diagnosed upto Dec. 2003. On analysis, it was observed that the mortality was maximum in the age-group of 41-50 years (25%), 24.4% in males and 24.2% in females. For patients with tuberculosis morality was 23% and was higher among those with unsafe sex (24.5%) as a risk factor. Mortality of AIDS patients in Delhi decreased from 63.2% in 1994 to 24.2% in the year 2003. Also tuberculosis was found to be the major opportunistic infection affecting 83.2% of the patients. An increasing trend was observed with tuberculosis from 84.2% in 1994 to 89.1% in 1997 (p<0.05), but overall tendency was around 84% during the period 1994 to 2003. In AIDS related symptoms chronic diarrheoa accounted for only 5.2%. The median length of survival of HIV infected patients with all subjects was 75 months. The hazard rate showed an increasing trend and reached its peak at 102 months. The survival of HIV infected patients in Delhi was found to be shorter than that of patients in developed countries and developing African countries.