Biomedical subjects

Takeshi Nawa

Publications and source records attributed to Takeshi Nawa.

6 recordsLinked to original sources

PubMed2026

A reanalysis of the Hitachi cohort study evaluating the effectiveness of low-dose CT screening for lung cancer.

The effectiveness of low-dose thoracic computed tomography (CT) screening for lung cancer for non-smokers or light smokers has been unclear. The results of the Hitachi cohort study performed by the conventional multivariable analysis suggested the reduction of lung cancer mortality by thoracic CT screening, but also revealed the lower all-cause mortality in the CT group, which indicated the existence of self-selection bias. Because the background of the subjects in the CT screening group and that in the X-ray screening group were very different, it is critical to adjust appropriately the confounding factors. In this brief report, we describe a re-evaluation of the results of the Hitachi Cohort Study performed by using more flexible methods, propensity score matching and inverse probability weighting.

epidemiology/public health↗

PubMed2004

Possible association between heavy computer users and glaucomatous visual field abnormalities: a cross sectional study in Japanese workers.

STUDY OBJECTIVE: To study the association between computer use and visual field abnormalities (VFA) and to assess whether heavy computer users have an increased risk of glaucoma. DESIGN: Cross sectional multicentre study. Subjects and observation procedures: A total of 10 202 randomly selected Japanese workers (mean (SD) age 43.2 (9.8) years) were screened for VFA using the frequency doubling technology perimetry (FDT-VFA), in addition to undergoing a general medical check up, and then ophthalmologically examined. Information about their computer use and refractive errors was obtained from a questionnaire and interview, respectively. MAIN RESULTS: As a result of FDT test, 522 and 8602 subjects were positive and negative for FDT-VFA, respectively. A significant (p = 0.004) interaction was found between computer use and refractive errors regarding the risk of FDT-VFA. In stratified analysis, heavy computer users with refractive errors showed a significant positive association with FDT-VFA (odds ratio (OR) = 1.74, 95% confidence interval (CI) 1.28 to 2.37), while those without refractive errors did not. Comparison of 165 subjects with an ophthalmological diagnosis of glaucoma and 2918 controls showed that the OR for glaucoma of heavy computer users with refractive errors was 1.82 (95% CI 1.06 to 3.12). Of 165 subjects with glaucoma, 141 had refractive errors, especially myopia (96.4%, 136 of 141). CONCLUSIONS: Although there are limitations to this study, such as its cross sectional design, heavy computer users with refractive errors seem to have an increased risk of FDT-VFA. Glaucoma might be involved in an underlying disease and myopia in a risk factor for FDT-VFA.

Adult↗

PubMed2003

Laterality of the performance of glaucoma mass screening using frequency-doubling technology.

PURPOSE: This study investigated laterality during the performance of glaucoma mass screening with a frequency-doubling technology perimetry test. MATERIALS AND METHODS: A frequency-doubling technology screening mode (C-20-1, version 2.6) test was performed on both eyes of 14,784 persons. Subjects with visual field abnormalities detected by the frequency-doubling technology test or with fixation error underwent retesting without a specified interval for rest. Consequently, 206 subjects who fulfilled the screening criteria of the frequency-doubling technology-based glaucoma screening protocol [FDT-GSP(+)] were further investigated using the Humphrey visual field analyzer (30-2). As a result, 74 right eyes and 57 left eyes were shown to have definite glaucoma. RESULTS: Frequency-doubling technology data for the left eye demonstrated a significantly (P<0.001) higher rate of artifacts, such as no reproducibility of results between the first and second tests (left/right: 2.4%/1.7%) as well as fixation errors (left/right: 2.8%/1.0%). The false-positive rate of the FDT-GSP for glaucoma was more than 1.5-fold higher in the left eye than in the right eye (16.3%/9.8%). In the case that either eye exhibited FDT-GSP(+), the positive predictive value of the FDT-GSP for definite glaucoma in the left eye was almost half of that in the right eye (28.4% vs. 53.8%). Specificity of the FDT-GSP for detection of definite glaucoma also exhibited a lower trend (P = 0.097) in the left eye (44.6%) than in the right eye (55.3%), but the sensitivity of the test was similar in both eyes (91.2% vs. 90.5%, respectively). CONCLUSIONS: When frequency-doubling technology-based mass screening is performed on the general population, performance is lower for the left eye than for the right eye. This performance disparity is likely to be primarily associated with a difference in specificity.

Adult↗

PubMed2002

Performance of glaucoma mass screening with only a visual field test using frequency-doubling technology perimetry.

PURPOSE: To report the performance of glaucoma mass screening with only a visual field test utilizing frequency- doubling technology (FDT) perimetry in general populations. DESIGN: Hospital and population-based cross-sectional study. METHODS: This study took place in a multicenter setting. One hundred three consecutive glaucomatous patients and 14,814 persons were randomly selected. We had created a glaucoma screening protocol (GSP) using FDT perimetry (FDT-GSP). Frequency-doubling technology-glaucoma screening protocol was tested on consecutive glaucoma patients diagnosed with Humphrey visual field analyzer (30-2 SITA standard), and then FDT-GSP was applied to general populations. Frequency-doubling technology-glaucoma screening protocol positive subjects were ophthalmologically diagnosed. Detection ability of FDT-GSP was determined in consecutive patients, and the positive predictive value (PPV) of FDT-GSP to detect definitive glaucoma was estimated in general populations. RESULTS: Frequency-doubling technique-glaucoma screening protocol detected 83.3% and 100% of definitive glaucoma patients with an early (mean deviation [MD] > -6 dB) and more advanced stage (MD < or = -6 dB), respectively. In the population-based screening, there were 660 (4.5%) subjects who had positive FDT-GSP, including 512 in whom no visual field abnormalities (VFA) had been pointed out previously. Of them, 370 subjects underwent ophthalmologic diagnosis. Then, 266 (71.9%, 266/370) subjects had a glaucomatous disk and 167 had definitive glaucomatous VFA. Fifty-five (14.9%) and 39 (10.5%) subjects were diagnosed as having other diseases and as normal, respectively. The PPV of FDT-GSP ranged from 32.6% (167/512)-45.1% (167/370). CONCLUSIONS: Frequency-doubling technology-based screening with only a visual field test showed reasonable performance on mass screening for detection of definitive glaucoma in this study population, considering the glaucoma prevalence.

Aged↗

PubMed2002

Lung cancer screening using low-dose spiral CT: results of baseline and 1-year follow-up studies.

STUDY OBJECTIVE: To evaluate the feasibility of lung cancer screening using low-dose spiral CT as a part of annual health examinations. DESIGN: Nonrandomized, screening practice. METHODS: From April 1998 to August 2000, CT screening was performed as a part of annual health examinations on a total of 7,956 individuals who belonged to the Hitachi Employee's Health Insurance Group. Of those participants, 5,568 were rescreened 1 year later. When a noncalcified solitary pulmonary nodule (SPN) >or= 8 mm was detected on CT screening, a detailed CT scan was carried out approximately 1 month later. RESULTS: During the baseline screening, a total of 2,865 noncalcified SPNs were detected among the 7,956 participants. Primary lung cancer was histologically confirmed in 40 patients (41 lesions). The prevalence was 0.44% of all participants from the baseline, and 0.07% from the repeated screening. Thirty-five of 41 tumors were stage I. Current or former smokers represented only 17 of 40 cases. The detection rate was rather high in female participants. CONCLUSION: Low-dose spiral CT seems to be a promising method for screening early lung cancer as a part of annual health examinations. Female and nonsmoking subjects should be included in the baseline screening. However, for yearly repeat screening, the participants may be selected on the basis of gender, smoking history, and results at the baseline screening.

Age Distribution↗

PubMed2002

[Prevalence of emphysematous changes as shown by low-dose spiral CT screening images in 6144 healthy subjects].

We assessed the prevalence of emphysematous changes among healthy workers and retired persons, using subjective evaluations of low-dose spiral CT images obtained during thoracic CT screenings for lung cancer. Among 6144 male participants (50-69 years old; mean age, 57), we detected 686 cases (11.2%) with emphysematous changes. The majority (95.3%) of CT-detected emphysema cases were in current or former smokers, and 169 cases (24.6%) showed significant obstructive impairment. Of 236 cases with emphysematous changes in the internal region (more than 20 mm from the costal margin), 98(41.5%) had significant obstructive impairment. Smoking was found to be the major risk factor for CT-detected emphysema. Longitudinal observation of the emphysema cases, as well as health care support for cessation of smoking, is very important.

Aged↗