Maiko Akutagawa

Relationship between Item Responses of Negative Affect Items and the Distribution of the Sum of the Item Scores in the General Population

Background Several studies have shown that total depressive symptom scores in the general population approximate an exponential pattern, except for the lower end of the distribution. The Center for Epidemiologic Studies Depression Scale (CES-D) consists of 20 items, each of which may take on four scores: “rarely,” “some,” “occasionally,” and “most of the time.” Recently, we reported that the item responses for 16 negative affect items commonly exhibit exponential patterns, except for the level of “rarely,” leading us to hypothesize that the item responses at the level of “rarely” may be related to the non-exponential pattern typical of the lower end of the distribution. To verify this hypothesis, we investigated how the item responses contribute to the distribution of the sum of the item scores. Methods Data collected from 21,040 subjects who had completed the CES-D questionnaire as part of a Japanese national survey were analyzed. To assess the item responses of negative affect items, we used a parameter r, which denotes the ratio of “rarely” to “some” in each item response. The distributions of the sum of negative affect items in various combinations were analyzed using log-normal scales and curve fitting. Results The sum of the item scores approximated an exponential pattern regardless of the combination of items, whereas, at the lower end of the distributions, there was a clear divergence between the actual data and the predicted exponential pattern. At the lower end of the distributions, the sum of the item scores with high values of r exhibited higher scores compared to those predicted from the exponential pattern, whereas the sum of the item scores with low values of r exhibited lower scores compared to those predicted. Conclusions The distributional pattern of the sum of the item scores could be predicted from the item responses of such items.

Boundary curves of individual items in the distribution of total depressive symptom scores approximate an exponential pattern in a general population

Background Previously, we proposed a model for ordinal scale scoring in which individual thresholds for each item constitute a distribution by each item. This lead us to hypothesize that the boundary curves of each depressive symptom score in the distribution of total depressive symptom scores follow a common mathematical model, which is expressed as the product of the frequency of the total depressive symptom scores and the probability of the cumulative distribution function of each item threshold. To verify this hypothesis, we investigated the boundary curves of the distribution of total depressive symptom scores in a general population. Methods Data collected from 21,040 subjects who had completed the Center for Epidemiologic Studies Depression Scale (CES-D) questionnaire as part of a national Japanese survey were analyzed. The CES-D consists of 20 items (16 negative items and four positive items). The boundary curves of adjacent item scores in the distribution of total depressive symptom scores for the 16 negative items were analyzed using log-normal scales and curve fitting. Results The boundary curves of adjacent item scores for a given symptom approximated a common linear pattern on a log normal scale. Curve fitting showed that an exponential fit had a markedly higher coefficient of determination than either linear or quadratic fits. With negative affect items, the gap between the total score curve and boundary curve continuously increased with increasing total depressive symptom scores on a log-normal scale, whereas the boundary curves of positive affect items, which are not considered manifest variables of the latent trait, did not exhibit such increases in this gap. Discussion The results of the present study support the hypothesis that the boundary curves of each depressive symptom score in the distribution of total depressive symptom scores commonly follow the predicted mathematical model, which was verified to approximate an exponential mathematical pattern.

Distributional patterns of item responses and total scores on the PHQ-9 in the general population: data from the National Health and Nutrition Examination Survey

BackgroundRecently, item responses and total scores on depression screening scales have been reported to have characteristic distributions in the general population. The distributional pattern of responses to the Patient Health Questionnaire-9 (PHQ-9) in the general population has not been well studied. Thus, we carried out a pattern analysis of the PHQ-9 item responses and total scores in US adults.MethodsData (5372 individuals) were drawn from the 2013–2014 National Health and Nutrition Examination Survey in the United States. The item responses and total score distributions of the PHQ-9 data were investigated with graphical analysis and exponential regression model.ResultsLines of item responses showed the same pattern among the nine items, characterized by crossing at a single point between “not at all” and “several days” and a parallel pattern from “several days” to “nearly every day” on a log-normal scale. The total score distribution of the PHQ-9 exhibited an exponential pattern, except for at the lower end of the distribution.ConclusionsThe present results support that the item responses and total scores on the PHQ-9 in the general population show the same characteristic patterns, consistent with the previous studies using the Center for Epidemiologic Studies Depression Scale (CES-D) and Kessler Screening Scale for Psychological Distress (K6).

Characteristic distribution of the total and individual item scores on the Kessler Screening Scale for Psychological Distress (K6) in US adults

BackgroundThe distributional pattern of total scores on depression screening scales in the general population has not been well studied. Recent studies suggest that the total scores on depression screening scales follow an exponential pattern, with the exception of the lower end of the distribution. To further investigate the findings, we determined the distributions of the total and individual item scores on the Kessler Screening Scale for Psychological Distress (K6).MethodsData were obtained from the National Survey of Midlife Development in the United States. Participants comprised 6,223 individuals between the ages of 25 and 74. The distributions of the total and individual item scores in various combinations were investigated with histograms and regression analysis.ResultsIrrespective of the combination of items, the total and individual item scores followed an exponential pattern except at the lower scores. The estimated rate parameters of regression analysis were similar among distributions with the same number of chosen items. At the lower scores, the distributional patterns of total scores varied according to the ratio of “a little” to “none” for each item response.ConclusionsThe present results have the potential to estimate the distribution of depressive symptoms in the general population. While the degree of depressive symptoms varies from individual to individual, an entire population may show a certain mathematical distribution.

Item Response Patterns on the Patient Health Questionnaire-8 in a Nationally Representative Sample of US Adults

Recent studies have shown that item responses on the Center for Epidemiologic Studies Depression Scale (CES-D) and Kessler Screening Scale for Psychological Distress (K6) exhibit the same characteristic item response patterns among the general population. However, the distributional patterns of responses on the Patient Health Questionnaire-8 (PHQ-8) among the general population have not been adequately studied. Thus, we conducted a pattern analysis of PHQ-8 item responses among US adults. Data (18,446 individuals) were obtained from the 2015 Behavioral Risk Factor Surveillance Survey (BRFSS). Item responses on the BRFSS version of the PHQ-8 were scored using the number of days response set and then converted to the original 4-point scale. The patterns of item responses were analyzed through graphical analysis. Lines of item responses scored using the number of days response set showed the same pattern among the eight items, characterized by crossing at a single point between “0 days” and “1 day,” and parallel fluctuation from “1 day” to “14 days” on a semi-logarithmic scale. Lines of item responses converted to the 4-point scale also showed the same characteristic pattern among the eight items. The present results demonstrate that the item responses on the PHQ-8 show the same characteristic patterns among items, consistent with the CES-D and the K6.

Regional differences in hepatitis C treatment with peginterferon and ribavirin in Japan in both genotype 1 and genotype 2: A retrospective cohort study

There has been no report on the genotype-dependent regional, especially prefectural, differences in hepatitis C treatment in Japan. We conducted a retrospective cohort study using the nationwide database. The registration period of the database was from December 2009 to April 2013. Individuals with chronic hepatitis C were identified from the database. The sustained virologic response (SVR) rates in each prefecture were calculated stratified by genotype. Confounding variables were identified using stepwise logistic regression analysis. The range of the point estimate of the adjusted odds ratio explained prefectural differences in treatment outcomes. During the registration period, 36 prefectures registered cases to the database. A total of 16349 cases were registered and 11653 cases were included in the analysis. The mean age was 57.9±10.5 years; 7950 (68.2%) had hepatitis C virus (HCV) genotype 1 and 3703 (31.8%) had HCV genotype 2. The range in SVR rates was 30.0 to 63.0% for genotype 1 and 55.0 to 100.0% for genotype 2. In the multivariate analysis, the ranges of the adjusted odds ratio of each prefecture were 0.658 to 2.125 for genotype 1 and 0.364 to 2.630 for genotype 2. Our results suggest that regional, particularly prefectural, differences in chronic hepatitis C treatment with peg-interferon (IFN) and ribavirin (RBV) exist in Japan and that these regional differences may similarly exist both in HCV genotypes 1 and 2. Additional studies using these methods, considering medical situations in each prefecture and new treatments regimens, could greatly contribute to improving and standardizing chronic hepatitis C treatment.

Distribution of item responses and total item scores for the Center for Epidemiologic Studies Depression Scale (CES-D): Data from the Irish Longitudinal Study on Ageing (TILDA)

Background Previous studies have shown that item responses and total scores on depression screening scales follow characteristic distribution patterns in the United States and Japanese general populations. However, the degree to which these findings, especially in terms of item responses, can be generalized to a European population is unknown. Thus, we analyzed the item responses and total score distribution for the Center for Epidemiologic Studies Depression Scale (CES-D) in a representative Irish cohort from a large, recent study—the Irish Longitudinal Study on Ageing (TILDA). Methods We used CES-D data from the 2009–2011 TILDA (8504 individuals). Responses for the 16 depressive symptoms included “rarely,” “some of the time,” “occasionally,” and “all of the time.” Item response patterns and total score distribution across these 16 depressive symptom items were examined using graphical analyses and exponential regression modeling. Results Lines for item responses followed the same pattern across the 16 items. These lines were characterized by intersections in the vicinity of a single point between “rarely” and “some of the time” and parallel patterns from “some of the time” to “all of the time” on a log-normal scale. Total scores for the 16 items exhibited an exponential pattern, except for at the lower end of the distribution. Conclusions The present findings suggest that item responses and total scores on depression screening scales among the general population follow the same characteristic patterns across populations from multiple nations.

Stability of the Distribution of Patient Health Questionnaire-9 Scores Against Age in the General Population: Data From the National Health and Nutrition Examination Survey

Background: Epidemiological studies using the nine-item Patient Health Questionnaire (PHQ-9) have reported inconsistencies regarding the relationship between age and total scores. To determine whether this discrepancy is due to the stability of the distribution of PHQ-9 total scores against age, we investigated whether the total score distribution remains stable during adulthood, and also investigated the mathematical patterns of the total score distribution. Methods: The present study utilized data from 15,847 participants of the 2009–2014 United States National Health and Nutrition Examination Survey, all of whom responded to all PHQ-9 items. The stability of the total score distribution among different age groups was examined using overlap coefficients and graphical analysis. Results: High overlap coefficients were observed between all age groups for the distributions of PHQ-9 total scores, suggesting that the distribution of PHQ-9 total scores remains stable against age. Graphical analysis demonstrated that distributions of PHQ-9 total scores were similar across age groups. In addition, distributions of PHQ-9 total scores exhibited an exponential pattern, except at the lower end of the distribution. Conclusions: Our findings indicate that the stability of the distribution of PHQ-9 total scores throughout adulthood may underlie inconsistencies in the evidence regarding age-related changes in total depression scores.

Safety profile of telaprevir-based triple therapy in elderly patients: A real-world retrospective cohort study

To compare the rate of treatment discontinuation due to adverse events for telaprevir-based triple (T/PR) and pegylated interferon-alfa-2b and ribavirin (PR) therapy for the treatment of hepatitis C virus (HCV) infection in patients over the age of 65 years, in Japan. Retrospective analysis of the health data of patients over the age of 65 years treated for a HCV infection genotype 1 using T/PR or PR therapy, from 38 prefectures in Japan. The primary outcome was the rate of treatment discontinuation due to adverse events for T/PR and PR. The secondary outcome was to evaluate the prevalence and type of adverse events during the treatment period that resulted in treatment discontinuation for both therapies. For comparison, the T/PR and PR populations were matched using the propensity score method, and adjusted odds ratios (ORs) for treatment discontinuation calculated by multivariate logistic regression analysis. The study group included 1330 patients, 328 in the T/PR group and 1002 in the PR group. The rate of treatment discontinuation due to adverse events in the matched population was lower for T/PR (19.82%) than PR (35.98%) therapy, (adjusted OR, 0.418; 95% confidence interval, 0.292-0.599; p<0.01). Malaise was the principal cause of treatment discontinuation in both groups (T/PR, 30.77%, and PR, 42.37%). Using real-world health data of elderly individuals in Japan, we identified a lower rate of treatment discontinuation for T/PR than PR. Our outcomes provide information for a segment of the population that is generally excluded for clinical trials.

Cost-outcome description of PEG-IFN-α2b + RBV for hepatitis C: results based on the interferon database

Economic evaluation of drugs is used in decision-making on medical care and public policy. Recently, real-world data (RWD) have been used in the analysis. In this study, we discuss the risk and benefits of using RWD for economic evaluation. We conducted a cost-outcome description with RWD from a nationwide registry providing information on hepatitis treatment in Japan and estimated the utility of the analysis. We evaluated the cost-outcome description of peginterferon plus ribavirin (PEG-IFN-α2b+RBV) treatment in hepatitis C virus (HCV)-infected patients. Simulations were based on a Markov model. The cohorts were set using data from the registry and we assumed a societal perspective for the calculation of costs. The dose and drug cost were chosen based on the Japanese Guidelines for the Management of Hepatitis C Virus Infection or package inserts. Model details and parameters were as described in previous studies. The simulations were performed for a period of 10 years with no discount rate. We estimated 2.5 million JPY per Quality Adjusted Life Year (QALY) in 48-week PEG-IFN-α2b+RBV treatment for a period of 10 years. The results of this study are in agreement with previous HCV treatment economic evaluation studies in Japan. We analyzed the statistics of the HCV-infected patients at each disease stage using the data in our registry and calculated the costs. The results of this study more closely reflect a real-world clinical situation compared to the widely used randomized clinical trial method, which estimates clinical trial results and scenarios.