Displaying publications 61 - 75 of 75 in total

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  1. Lee LH, Cheah YK, Mohd Sidik S, Ab Mutalib NS, Tang YL, Lin HP, et al.
    World J Microbiol Biotechnol, 2012 May;28(5):2125-37.
    PMID: 22806035 DOI: 10.1007/s11274-012-1018-1
    The present study aimed to isolate actinobacteria from soil samples and characterized them using molecular tools and screened their secondary metabolites for antimicrobial activities. Thirty-nine strains from four different location of Barrientos Island, Antarctica using 12 types of isolation media was isolated. The isolates were preceded to screening of secondary metabolites for antimicrobial and antifungal activities. Using high-throughput screening methods, 38% (15/39) of isolates produced bioactive metabolites. Approximately 18% (7/39), 18% (7/39), 10% (4/39) and 2.5% (1/39) of isolates inhibited growth of Candida albicans ATCC 10231(T), Staphylococcus aurues ATCC 51650(T), methicillin-resistant Staphylococcus aurues (MRSA) ATCC BAA-44(T) and Pseudomonas aeruginosa ATCC 10145(T), respectively. Molecular characterization techniques like 16S rRNA analysis, Enterobacterial repetitive intergenic consensus-polymerase chain reaction (ERIC-PCR), Random amplified polymorphic DNA (RAPD) and composite analyses were used to characterize the actinobacteria strains. Analysis of 16S rRNA sequences is still one of the most powerful methods to determine higher taxonomic relationships of Actinobacteria. Both RAPD and ERIC-PCR fingerprinting have shown good discriminatory capability but RAPD proved to be better in discriminatory power than ERIC-PCR. Our results demonstrated that composite analysis of both fingerprinting generally increased the discrimination ability and generated best clustering for actinobacteria strains in this study.
  2. Karim AH, Jalil AA, Triwahyono S, Sidik SM, Kamarudin NH, Jusoh R, et al.
    J Colloid Interface Sci, 2012 Nov 15;386(1):307-14.
    PMID: 22889626 DOI: 10.1016/j.jcis.2012.07.043
    In this work, mesostructured silica nanoparticles (MSN(AP)) with high adsorptivity were prepared by a modification with 3-aminopropyl triethoxysilane (APTES) as a pore expander. The performance of the MSN(AP) was tested by the adsorption of MB in a batch system under varying pH (2-11), adsorbent dosage (0.1-0.5 g L(-1)), and initial MB concentration (5-60 mg L(-1)). The best conditions were achieved at pH 7 when using 0.1 g L(-1) MSN(AP) and 60 mg L(-1)MB to give a maximum monolayer adsorption capacity of 500.1 mg g(-1) at 303 K. The equilibrium data were evaluated using the Langmuir, Freundlich, Temkin, and Harkins-Jura isotherms and fit well to the Freundlich isotherm model. The adsorption kinetics was best described by the pseudo-second order model. The results indicate the potential for a new use of mesostructured materials as an effective adsorbent for MB.
  3. Lim JC, Goh FY, Sagineedu SR, Yong AC, Sidik SM, Lajis NH, et al.
    Toxicol Appl Pharmacol, 2016 07 01;302:10-22.
    PMID: 27089844 DOI: 10.1016/j.taap.2016.04.004
    Andrographolide (AGP) and 14-deoxy-11,12-didehydroandrographolide (DDAG), two main diterpenoid constituents of Andrographis paniculata were previously shown to ameliorate asthmatic symptoms in a mouse model. However, due to inadequacies of both compounds in terms of drug-likeness, DDAG analogues were semisynthesised for assessment of their anti-asthma activity. A selected analogue, 3,19-diacetyl-14-deoxy-11,12-didehydroandrographolide (SRS27), was tested for inhibitory activity of NF-κB activation in TNF-α-induced A549 cells and was subsequently evaluated in a mouse model of ovalbumin (OVA)-induced asthma. Female BALB/c mice, 6-8weeks old were sensitized on days 0 and 14, and challenged on days 22, 23 and 24 with OVA. Compound or vehicle (3% dimethyl sulfoxide) was administered intraperitoneally 1h before and 11h after each OVA aerosol challenge. On day 25, pulmonary eosinophilia, airway hyperresponsiveness, mucus hypersecretion, inflammatory cytokines such as IL-4, -5 and -13 in BAL fluid, gene expression of inflammatory mediators such as 5-LOX, E-selectin, VCAM-1, CCL5, TNF-α, AMCase, Ym2, YKL-40, Muc5ac, CCL2 and iNOS in animal lung tissues, and serum IgE were determined. SRS27 at 30μM was found to suppress NF-κB nuclear translocation in A549 cells. In the ovalbumin-induced mouse asthma model, SRS27 at 3mg/kg displayed a substantial decrease in pulmonary eosinophilia, BAL fluid inflammatory cytokines level, serum IgE production, mucus hypersecretion and gene expression of inflammatory mediators in lung tissues. SRS27 is the first known DDAG analogue effective in ameliorating inflammation and airway hyperresponsiveness in the ovalbumin-induced mouse asthma model.
  4. Lekhraj Rampal GR, Mohd Sidik S, Rampal S, Daniel Wong YJ, Chow PL, Liew JS, et al.
    Malays J Nutr, 2007 Mar;13(1):1-8.
    PMID: 22692184 MyJurnal
    Overweight and obesity place children and adolescents at increased risk of significant health problems, both during their early life and adult life. A cross sectional study was carried out to determine the prevalence of overweight among secondary school students aged 13-17 years in the Klang district and to determine the association between overweight and age, sex, ethnicity, religion and blood pressure. Random cluster proportionate to size sampling technique was used to select the respondents. Weight was recorded using TANITA model HD-309 and height was measured using SECA Body meter Model 208. A mercury sphygmomanometer was used to measure blood pressure manually. Statistical analysis was carried out using SPSS version 13. Out of the 3,333 respondents, 11.4% were found to be at risk of overweight and 8.2% were overweight. The prevalence of overweight was significantly higher in the males (10.6%) as compared to females (6.0%). Prevalence of overweight was highest in Malays (10.7%) followed by the Indians (7.1%) and the Chinese (5.9%). Prevalence of 'risk of overweight' was highest in the Indians (13.7%) followed by Chinese (12.0%) and Malays (9.8%). There was a moderate direct significant relationship between overweight and systolic blood pressure (r=0.5, r2=0.25, p<0.001) and also diastolic blood pressure (r=0.42, r2=0.18, p<0.001). The relationship between BMI and overweight was very weak (r=0.11, r2=0.01 and df=3331, p<0.001). In conclusion the prevalence of overweight among the secondary school students is high and there is a need for a comprehensive integrated population-based intervention program.
  5. Tan CE, Lau SCD, Tan KA, Latiff ZA, Teh KH, Lee CC, et al.
    Cureus, 2022 Oct;14(10):e30903.
    PMID: 36465778 DOI: 10.7759/cureus.30903
    Introduction Validated tools to measure caregiving knowledge among parents of children with hematological cancers are needed to measure the clinical outcome of caregiver interventions. This study reports the development and validation of the Hematological Oncology Parents Education Caregiving Knowledge Questionnaire (HOPE-CKQ) among Malaysian parents of pediatric leukemia and lymphoma patients. Methods Initially, 60 items on caregiving knowledge were developed based on a qualitative needs assessment study. Content validity was evaluated using item content validity index (I-CVI) and scale content validity index (S-CVI/Ave). Parents of pediatric leukemia and lymphoma patients were invited to complete the 60-item version of the HOPE-CKQ. Exploratory factor analysis (EFA) using polychoric correlation resulted in an 18-item version of HOPE-CKQ. Confirmatory factor analysis (CFA) was used to verify the factor structure. Known-group validity was tested by comparing the scores among different levels of parent education. Results The I-CVI ranged from 0.83 to 1.00 whereas the S-CVI/Ave was 0.99, indicating good content validity. A total of 167 complete responses were analyzed for factor analysis. EFA using polychoric correlations resulted in a single-factor structure consisting of 18 items. CFA confirmed that the 18-item single-factor HOPE-CKQ model had a good fit for the data. The internal consistency reliability was good (α=0.80). Parents with tertiary education level had higher caregiving knowledge (M=12.61, SD=3.37) compared to parents with secondary education and below (M=10.33, SD=3.80) (t=3.58, p<0.001). Conclusions The 18-item HOPE-CKQ is valid and reliable for use to measure caregiving knowledge among pediatric leukemia and lymphoma parents. This tool may be considered to measure caregiving knowledge in future preventive and intervention programs.
  6. Yap SY, Foo CN, Lim YM, Ng FL, Mohd-Sidik S, Tang PY, et al.
    Int J Environ Res Public Health, 2021 May 18;18(10).
    PMID: 34069915 DOI: 10.3390/ijerph18105366
    Depression is commonly observed in university students, who are a high risk group for developing psychiatric disorders during adulthood. This study aimed to determine the prevalence of depression and its traditional Chinese medicine body constitutions and psychological determinants among university students in Malaysia. A cross-sectional pilot study was conducted between 9 and 28 September 2020 among 80 university students in Malaysia. Participants completed online survey questionnaires, including the validated Patient Health Questionnaire (PHQ-9), Constitution in Chinese Medicine Questionnaire (CMCQ), Dysfunctional Attitude Scale (DAS), Depression Anxiety Stress Scale (DASS-21) stress subscale, Perceived Stress Scale (PSS-10), and Rosenberg Self-Esteem Scale (RSES), which assess depression, body constitution, dysfunctional attitude, stress, perceived stress, and self-esteem. Multiple linear regression analyses were performed to determine the associated risk factors for depression. The overall prevalence of depression among university students was 33.8%. The multiple regression analysis showed a significant relationship between depression and qi-stagnation constitution (B = 0.089, p = 0.011), balanced constitution (B = -0.077, p = 0.049), and self-esteem (B = -0.325, p = 0.001). Our findings suggest that some traditional Chinese medicine body constitutions and self-esteem are significant risk factors affecting depression among university students. Identifying risk factors of depression is vital to aid in the early detection of depression among university students.
  7. Osman ZJ, Mukhtar F, Hashim HA, Abdul Latiff L, Mohd Sidik S, Awang H, et al.
    Compr Psychiatry, 2014 Oct;55(7):1720-5.
    PMID: 24952938 DOI: 10.1016/j.comppsych.2014.04.011
    OBJECTIVE: The 21-item Depression, Anxiety and Stress Scale (DASS-21) is frequently used in non-clinical research to measure mental health factors among adults. However, previous studies have concluded that the 21 items are not stable for utilization among the adolescent population. Thus, the aims of this study are to examine the structure of the factors and to report on the reliability of the refined version of the DASS that consists of 12 items.
    METHOD: A total of 2850 students (aged 13 to 17 years old) from three major ethnic in Malaysia completed the DASS-21. The study was conducted at 10 randomly selected secondary schools in the northern state of Peninsular Malaysia. The study population comprised secondary school students (Forms 1, 2 and 4) from the selected schools.
    RESULTS: Based on the results of the EFA stage, 12 items were included in a final CFA to test the fit of the model. Using maximum likelihood procedures to estimate the model, the selected fit indices indicated a close model fit (χ(2)=132.94, df=57, p=.000; CFI=.96; RMR=.02; RMSEA=.04). Moreover, significant loadings of all the unstandardized regression weights implied an acceptable convergent validity. Besides the convergent validity of the item, a discriminant validity of the subscales was also evident from the moderate latent factor inter-correlations, which ranged from .62 to .75. The subscale reliability was further estimated using Cronbach's alpha and the adequate reliability of the subscales was obtained (Total=76; Depression=.68; Anxiety=.53; Stress=.52).
    CONCLUSION: The new version of the 12-item DASS for adolescents in Malaysia (DASS-12) is reliable and has a stable factor structure, and thus it is a useful instrument for distinguishing between depression, anxiety and stress.
  8. Jalil AA, Triwahyono S, Yaakob MR, Azmi ZZ, Sapawe N, Kamarudin NH, et al.
    Bioresour Technol, 2012 Sep;120:218-24.
    PMID: 22820110 DOI: 10.1016/j.biortech.2012.06.066
    In this work, two low-cost wastes, bivalve shell (BS) and Zea mays L. husk leaf (ZHL), were investigated to adsorb malachite green (MG) from aqueous solutions. The ZHL was treated with calcined BS to give the BS-ZHL, and its ability to adsorb MG was compared with untreated ZHL, calcined BS and Ca(OH)(2)-treated ZHL under several different conditions: pH (2-8), adsorbent dosage (0.25-2.5 g L(-1)), contact time (10-30 min), initial MG concentration (10-200 mg L(-1)) and temperature (303-323 K). The equilibrium studies indicated that the experimental data were in agreement with the Langmuir isotherm model. The use of 2.5 g L(-1) BS-ZHL resulted in the nearly complete removal of 200 mg L(-1) of MG with a maximum adsorption capacity of 81.5 mg g(-1) after 30 min of contact time at pH 6 and 323 K. The results indicated that the BS-ZHL can be used to effectively remove MG from aqueous media.
  9. Ganapathy SS, Sooryanarayana R, Ahmad NA, Jamaluddin R, Abd Razak MA, Tan MP, et al.
    Geriatr Gerontol Int, 2020 Dec;20 Suppl 2:16-20.
    PMID: 33370858 DOI: 10.1111/ggi.14031
    AIM: Dementia is the major cause of disability among older persons and leading physical and psychological sequelae for both the person living with dementia (PLwD) and their caregivers. The aim of this study was to determine the prevalence of dementia in Malaysia and identify the factors influencing quality of life (QoL) of caregivers of PLwD.

    METHODS: A nationwide survey was conducted among individuals aged ≥60 years. Cognition was assessed with the Identification and Intervention for Dementia in Elderly Africans (IDEA) tool. QoL of older caregivers was assessed using the Control, Autonomy, Self-Realization and Pleasure (CASP-19) questionnaire.

    RESULTS: The prevalence of dementia among older adults aged ≥60 years in Malaysia was found to be 8.5%. The prevalence was found to be higher among females, those with no formal education and those in rural areas in Malaysia. The mean QoL of family caregivers of PLwD was significantly lower than the caregivers of older adults without dementia were (P 

  10. Ahmad NA, Abd Razak MA, Kassim MS, Sahril N, Ahmad FH, Harith AA, et al.
    Geriatr Gerontol Int, 2020 Dec;20 Suppl 2:21-25.
    PMID: 33370850 DOI: 10.1111/ggi.14012
    AIM: This study aimed to assess the relationship between functional limitations and depression among community-dwelling older adults in Malaysia.

    METHODS: Data from a nation-wide community-based cross-sectional study were analyzed. This study was conducted using a two-stage stratified random sampling design. In total, 3772 older adults aged ≥60 years responded to the survey. Depression was identified using a validated Malay version of the Geriatric Depression Scale (M-GDS-14), with those scored ≥6 categorized as having depression. Functional limitations were assessed using both Barthel's Activities of Daily Living (ADL) and Lawton's Instrumental Activities of Daily Living (IADL). The relationship was determined by multivariate logistic regression, adjusted for other variables.

    RESULTS: The prevalence of depression was 11.5% (95% confidence interval [CI] 9.4, 13.4). Multiple logistic regression analysis found that older adults with limitations in ADL were 2.6 times more likely of having depression (adjusted odds ratio [aOR] 2.58, 95% CI 2.01, 3.32), while those with limitations in IADL the risk of having depression was almost doubled (aOR 1.68, 95% CI: 1.32, 2.14). Other significant factors were incontinence (aOR 3.33, 95% CI: 2.33, 4.74), chronic medical illness (aOR 1.44, 95% CI: 1.15, 1.81), current smoker (aOR 4.19, 95% CI: 1.69, 10.39), poor social support (aOR 4.30, 95% CI: 2.98, 6.20), do not have partner, ethnic minorities and low individual monthly income.

    CONCLUSIONS: Older adults with functional limitation in both basic ADL and complex IADL are independently at higher risk of having depression. Geriatr Gerontol Int 2020; 20: 21-25.

  11. Ponka D, Coffman M, Fraser-Barclay KE, Fortier RDW, Howe A, Kidd M, et al.
    BMJ Glob Health, 2020 07;5(7).
    PMID: 32624501 DOI: 10.1136/bmjgh-2020-002470
    The Alma Ata and Astana Declarations reaffirm the importance of high-quality primary healthcare (PHC), yet the capacity to undertake PHC research-a core element of high-quality PHC-in low-income and middle-income countries (LMIC) is limited. Our aim is to explore the current risks or barriers to primary care research capacity building, identify the ongoing tensions that need to be resolved and offer some solutions, focusing on emerging contexts. This paper arose from a workshop held at the 2019 North American Primary Care Research Group Annual Meeting addressing research capacity building in LMICs. Five case studies (three from Africa, one from South-East Asia and one from South America) illustrate tensions and solutions to strengthening PHC research around the world. Research must be conducted in local contexts and be responsive to the needs of patients, populations and practitioners in the community. The case studies exemplify that research capacity can be strengthened at the micro (practice), meso (institutional) and macro (national policy and international collaboration) levels. Clinicians may lack coverage to enable research time; however, practice-based research is precisely the most relevant for PHC. Increasing research capacity requires local skills, training, investment in infrastructure, and support of local academics and PHC service providers to select, host and manage locally needed research, as well as to disseminate findings to impact local practice and policy. Reliance on funding from high-income countries may limit projects of higher priority in LMIC, and 'brain drain' may reduce available research support; however, we provide recommendations on how to deal with these tensions.
  12. Wu Y, Levis B, Riehm KE, Saadat N, Levis AW, Azar M, et al.
    Psychol Med, 2020 06;50(8):1368-1380.
    PMID: 31298180 DOI: 10.1017/S0033291719001314
    BACKGROUND: Item 9 of the Patient Health Questionnaire-9 (PHQ-9) queries about thoughts of death and self-harm, but not suicidality. Although it is sometimes used to assess suicide risk, most positive responses are not associated with suicidality. The PHQ-8, which omits Item 9, is thus increasingly used in research. We assessed equivalency of total score correlations and the diagnostic accuracy to detect major depression of the PHQ-8 and PHQ-9.

    METHODS: We conducted an individual patient data meta-analysis. We fit bivariate random-effects models to assess diagnostic accuracy.

    RESULTS: 16 742 participants (2097 major depression cases) from 54 studies were included. The correlation between PHQ-8 and PHQ-9 scores was 0.996 (95% confidence interval 0.996 to 0.996). The standard cutoff score of 10 for the PHQ-9 maximized sensitivity + specificity for the PHQ-8 among studies that used a semi-structured diagnostic interview reference standard (N = 27). At cutoff 10, the PHQ-8 was less sensitive by 0.02 (-0.06 to 0.00) and more specific by 0.01 (0.00 to 0.01) among those studies (N = 27), with similar results for studies that used other types of interviews (N = 27). For all 54 primary studies combined, across all cutoffs, the PHQ-8 was less sensitive than the PHQ-9 by 0.00 to 0.05 (0.03 at cutoff 10), and specificity was within 0.01 for all cutoffs (0.00 to 0.01).

    CONCLUSIONS: PHQ-8 and PHQ-9 total scores were similar. Sensitivity may be minimally reduced with the PHQ-8, but specificity is similar.

  13. Levis B, Benedetti A, Riehm KE, Saadat N, Levis AW, Azar M, et al.
    Br J Psychiatry, 2018 06;212(6):377-385.
    PMID: 29717691 DOI: 10.1192/bjp.2018.54
    BACKGROUND: Different diagnostic interviews are used as reference standards for major depression classification in research. Semi-structured interviews involve clinical judgement, whereas fully structured interviews are completely scripted. The Mini International Neuropsychiatric Interview (MINI), a brief fully structured interview, is also sometimes used. It is not known whether interview method is associated with probability of major depression classification.AimsTo evaluate the association between interview method and odds of major depression classification, controlling for depressive symptom scores and participant characteristics.

    METHOD: Data collected for an individual participant data meta-analysis of Patient Health Questionnaire-9 (PHQ-9) diagnostic accuracy were analysed and binomial generalised linear mixed models were fit.

    RESULTS: A total of 17 158 participants (2287 with major depression) from 57 primary studies were analysed. Among fully structured interviews, odds of major depression were higher for the MINI compared with the Composite International Diagnostic Interview (CIDI) (odds ratio (OR) = 2.10; 95% CI = 1.15-3.87). Compared with semi-structured interviews, fully structured interviews (MINI excluded) were non-significantly more likely to classify participants with low-level depressive symptoms (PHQ-9 scores ≤6) as having major depression (OR = 3.13; 95% CI = 0.98-10.00), similarly likely for moderate-level symptoms (PHQ-9 scores 7-15) (OR = 0.96; 95% CI = 0.56-1.66) and significantly less likely for high-level symptoms (PHQ-9 scores ≥16) (OR = 0.50; 95% CI = 0.26-0.97).

    CONCLUSIONS: The MINI may identify more people as depressed than the CIDI, and semi-structured and fully structured interviews may not be interchangeable methods, but these results should be replicated.Declaration of interestDrs Jetté and Patten declare that they received a grant, outside the submitted work, from the Hotchkiss Brain Institute, which was jointly funded by the Institute and Pfizer. Pfizer was the original sponsor of the development of the PHQ-9, which is now in the public domain. Dr Chan is a steering committee member or consultant of Astra Zeneca, Bayer, Lilly, MSD and Pfizer. She has received sponsorships and honorarium for giving lectures and providing consultancy and her affiliated institution has received research grants from these companies. Dr Hegerl declares that within the past 3 years, he was an advisory board member for Lundbeck, Servier and Otsuka Pharma; a consultant for Bayer Pharma; and a speaker for Medice Arzneimittel, Novartis, and Roche Pharma, all outside the submitted work. Dr Inagaki declares that he has received grants from Novartis Pharma, lecture fees from Pfizer, Mochida, Shionogi, Sumitomo Dainippon Pharma, Daiichi-Sankyo, Meiji Seika and Takeda, and royalties from Nippon Hyoron Sha, Nanzando, Seiwa Shoten, Igaku-shoin and Technomics, all outside of the submitted work. Dr Yamada reports personal fees from Meiji Seika Pharma Co., Ltd., MSD K.K., Asahi Kasei Pharma Corporation, Seishin Shobo, Seiwa Shoten Co., Ltd., Igaku-shoin Ltd., Chugai Igakusha and Sentan Igakusha, all outside the submitted work. All other authors declare no competing interests. No funder had any role in the design and conduct of the study; collection, management, analysis and interpretation of the data; preparation, review or approval of the manuscript; and decision to submit the manuscript for publication.

  14. He C, Levis B, Riehm KE, Saadat N, Levis AW, Azar M, et al.
    Psychother Psychosom, 2020;89(1):25-37.
    PMID: 31593971 DOI: 10.1159/000502294
    BACKGROUND: Screening for major depression with the Patient Health Questionnaire-9 (PHQ-9) can be done using a cutoff or the PHQ-9 diagnostic algorithm. Many primary studies publish results for only one approach, and previous meta-analyses of the algorithm approach included only a subset of primary studies that collected data and could have published results.

    OBJECTIVE: To use an individual participant data meta-analysis to evaluate the accuracy of two PHQ-9 diagnostic algorithms for detecting major depression and compare accuracy between the algorithms and the standard PHQ-9 cutoff score of ≥10.

    METHODS: Medline, Medline In-Process and Other Non-Indexed Citations, PsycINFO, Web of Science (January 1, 2000, to February 7, 2015). Eligible studies that classified current major depression status using a validated diagnostic interview.

    RESULTS: Data were included for 54 of 72 identified eligible studies (n participants = 16,688, n cases = 2,091). Among studies that used a semi-structured interview, pooled sensitivity and specificity (95% confidence interval) were 0.57 (0.49, 0.64) and 0.95 (0.94, 0.97) for the original algorithm and 0.61 (0.54, 0.68) and 0.95 (0.93, 0.96) for a modified algorithm. Algorithm sensitivity was 0.22-0.24 lower compared to fully structured interviews and 0.06-0.07 lower compared to the Mini International Neuropsychiatric Interview. Specificity was similar across reference standards. For PHQ-9 cutoff of ≥10 compared to semi-structured interviews, sensitivity and specificity (95% confidence interval) were 0.88 (0.82-0.92) and 0.86 (0.82-0.88).

    CONCLUSIONS: The cutoff score approach appears to be a better option than a PHQ-9 algorithm for detecting major depression.

  15. Levis B, Bhandari PM, Neupane D, Fan S, Sun Y, He C, et al.
    JAMA Netw Open, 2024 Nov 04;7(11):e2429630.
    PMID: 39576645 DOI: 10.1001/jamanetworkopen.2024.29630
    IMPORTANCE: Test accuracy studies often use small datasets to simultaneously select an optimal cutoff score that maximizes test accuracy and generate accuracy estimates.

    OBJECTIVE: To evaluate the degree to which using data-driven methods to simultaneously select an optimal Patient Health Questionnaire-9 (PHQ-9) cutoff score and estimate accuracy yields (1) optimal cutoff scores that differ from the population-level optimal cutoff score and (2) biased accuracy estimates.

    DESIGN, SETTING, AND PARTICIPANTS: This study used cross-sectional data from an existing individual participant data meta-analysis (IPDMA) database on PHQ-9 screening accuracy to represent a hypothetical population. Studies in the IPDMA database compared participant PHQ-9 scores with a major depression classification. From the IPDMA population, 1000 studies of 100, 200, 500, and 1000 participants each were resampled.

    MAIN OUTCOMES AND MEASURES: For the full IPDMA population and each simulated study, an optimal cutoff score was selected by maximizing the Youden index. Accuracy estimates for optimal cutoff scores in simulated studies were compared with accuracy in the full population.

    RESULTS: The IPDMA database included 100 primary studies with 44 503 participants (4541 [10%] cases of major depression). The population-level optimal cutoff score was 8 or higher. Optimal cutoff scores in simulated studies ranged from 2 or higher to 21 or higher in samples of 100 participants and 5 or higher to 11 or higher in samples of 1000 participants. The percentage of simulated studies that identified the true optimal cutoff score of 8 or higher was 17% for samples of 100 participants and 33% for samples of 1000 participants. Compared with estimates for a cutoff score of 8 or higher in the population, sensitivity was overestimated by 6.4 (95% CI, 5.7-7.1) percentage points in samples of 100 participants, 4.9 (95% CI, 4.3-5.5) percentage points in samples of 200 participants, 2.2 (95% CI, 1.8-2.6) percentage points in samples of 500 participants, and 1.8 (95% CI, 1.5-2.1) percentage points in samples of 1000 participants. Specificity was within 1 percentage point across sample sizes.

    CONCLUSIONS AND RELEVANCE: This study of cross-sectional data found that optimal cutoff scores and accuracy estimates differed substantially from population values when data-driven methods were used to simultaneously identify an optimal cutoff score and estimate accuracy. Users of diagnostic accuracy evidence should evaluate studies of accuracy with caution and ensure that cutoff score recommendations are based on adequately powered research or well-conducted meta-analyses.

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