Use of wild fish and other aquatic organisms as feed in aquaculture; a review of practices and implications in the Asia Pacific

Global and Asian aquaculture have witnessed a ten-fold increase in production from 1980 to 2004. However, the relative percent contribution to production of each of the major commodities has remained almost unchanged. For example, the contribution of freshwater finfish has declined from 71 to 66 percent in Asia but has remained unchanged globally over the last 20 to 30 years. This fact has dictated trends in the use of fish as a feed for cultured stocks. The growth in the sector has gone hand in hand with an increasing dependence on fish as feed, either directly or indirectly. In a number of countries in the Asia-Pacific region, the aquaculture sector has surpassed the capture fisheries sector in its respective contributions to the gross domestic product (GDP). Aquaculture’s increased contribution to national GDPs can be taken as a clear indication of the contribution of the sector to food security and poverty alleviation. The use of finfish and other aquatic organisms as a feed source can be through direct utilization of whole or chopped raw fish in wet form, through fishmeal and fish oil in formulated feeds, and/or as live fish, although the latter is uncommon and the overall amounts used are relatively small. In the first two categories, the fish used are often termed “trash fish/low-value fish”. Although attempts have been made to define this term, all definitions have a certain degree of ambiguity and/or subjectivity. In this regional review, the amount of fish used as feed sources based on the above categories was estimated primarily from the production data, supported by assumptions on the inclusion levels of fishmeal in formulated feeds and observed feed conversion efficiencies for both formulated feeds and for stock fed trash fish/low-value fish directly. A scenario for the use of fish as feed was developed by starting from the levels of aquaculture production recorded in 2004 and assuming increases in production volumes of 10, 15 and 20 percent by 2010, respectively, for the three trajectories. In parallel, the pattern of wild fish use as feed was projected to change as fish and shrimp farmers increasingly replace farmmade feeds by incorporating trash fish/low-value fish with manufactured feeds that include fishmeal. Also, the fishmeal inclusion rates in manufactured feeds are falling slowly, and this has been incorporated into the projections. The regional review also deals with the production of fishmeal using trash fish/low-value fish in the Asia-Pacific region. Regional fishmeal production as a whole is relatively low when compared with that of major fishmeal-producing countries such as Chile, Iceland and Norway, amounting to approximately 1 million tonnes per year. However, there is a trend towards increasing the use of fish industry waste, such as from the tuna canning industry in Thailand. The fishmeal produced in the region is priced considerably lower than globally traded fishmeal, but its quality is poorer. Total fishmeal use in Asian aquaculture in 2004 was estimated as 2 388 million tonnes, the highest proportion of this being used for crustacean aquaculture (1 418 million tonnes). Based on growth predictions (to year 2010) in the sector and improvements to feed quality and management, it is expected that the quantity of fishmeal used in Asian aquaculture will be slightly less than at present. An estimated 240 000 tonnes of fish oil is used in Asian aquaculture, principally in shrimp feeds. Based on production estimates of commodities in 2004 that rely on trash fish/low-value fish as the main feed source, this regional review suggests that Asian aquaculture currently uses between 2 465 and 3 882 million tonnes, an amount that is predicted to decrease to between 1.890 and 2 795 million tonnes by 2010. The use of trash fish/low-value fish and fishmeal by the aquaculture sector has been repeatedly adjudicated as a non-sustainable practice, and globally the sector is seeking to reduce its dependence on fish as feed through improved feed management practices and development of better quality feeds and feed formulations using alternative ingredients. Over the next few years, decreases in the use of trash fish/low-value fish are also expected to be achieved through better conversion of raw materials into fishmeal and fish oil during the reduction processes. The “way forward” in addressing the issue of the use of fish as feed in aquaculture in the Asia-Pacific region includes the need for a concerted regional research thrust to reduce the use of fish as feed sources in aquaculture, as has been achieved in the animal husbandry sector. Secondly, there is a need to increase farmer awareness on the use of trash fish as feed. This is achievable, considering the similar progress that has been made by the region’s shrimp farming sector, which almost exclusively involves small-scale practitioners who are often clustered in a given locality. The analysis also suggests that the use of trash fish/low-value fish in aquaculture may be compatible with improving food security and alleviating poverty. In Asia, trash fish/low-value fish is mostly landed in areas where there are other suitable fish commodities for human consumption. To make the trash fish/low-value fish suitable and available for human consumption would involve some degree of value-adding and transportation costs, which are likely to increase the price to beyond the means of the consumer, particularly in remote rural areas. Under such a scenario, the direct or indirect use of this perishable resource as a feed source to produce a consumable commodity appears to make economic sense and appears to be the most logical use for overall human benefit. In this manner, trash fish/low-value fish contributes to food security by increasing income generation opportunities and hence contributes to poverty alleviation. Another factor that needs to be taken into account is the large numbers of artisanal fishers who harvest this raw material. The continued use of trash fish/low-value fish, therefore, allows these fishers to maintain their livelihoods¹. Admittedly, this is an area that warrants more detailed investigation, from resource use, livelihoods and economic viewpoints.

Solvent-induced 7R-dioxygenase activity of soybean 15-lipoxygenase-1 in the formation of omega-3 DPA-derived resolvin analogs

The resolvin family contains important anti-inflammatory and pro-resolution compounds enzymatically derived in vivo from the polyunsaturated omega-3 fatty acids, eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). More recently, docosapentaenoic acid (DPA) has emerged as another potentially important precursor in the biological production of resolvin compounds. In this work we have used medium engineering to develop a simple method for the controlled synthesis of two di-hydroxylated diastereomers of DPAn-3 catalyzed by soybean 15-lipoxygenase-1 (15-sLOX-1) in the presence of short chain n-alcohols, including methanol, ethanol and propan-1-ol. The complete structures of the two major products, 7S,17S-dihydroxydocosapenta-8Z,10E,13Z,15E,19Z-enoic acid (7S,17S-diHDPAn-3) and 7R,17S-dihydroxydocosapenta-8Z,10E,13Z,15E,19Z- enoic acid (7R,17S-diHDPAn-3), have been elucidated using spectroscopic analysis. The alcohol-dependent R-dioxygenase activity of soybean 15-lipoxygenase with mono-hydroperoxide intermediate substrates has also been demonstrated with other biologically relevant PUFAs, including DHA, EPA and ARA. The developed method has applications in the production of closely related isomers of naturally occurring resolvins and protectins, demonstrating the versatility of 15-sLOX-1 as a biocatalyst. © 2014 Elsevier B.V.

Oligomethylene-bridged dinuclear triorganotin triflates and diphenylphosphinates. Ion pairing in the solid state and electrolytic dissociation in solution of [Ph2Sn(CH2)nSnPh2X](O3SCF3) (X = OH, O2PPh2; n = 1-3)

The condensation of [Ph₂(OH)Sn(CH₂)_nSn(OH)Ph₂] (1-3; n = 1-3) with HO₃SCF₃ and HO₂PPh₂ provided [Ph₂Sn(CH₂)_nSnPh₂(OH)](O₃SCF₃) (4-6; n = 1-3) and [Ph₂(O₂PPh₂)Sn(CH₂)_nSn(O₂PPh₂)Ph₂] (10-12; n = 1-3), respectively. The reaction of [Ph₂Sn(CH₂)_nSnPh₂(OH)](O₃SCF₃) (4-6; n = 1-3) with HO₂PPh₂ and NaO₂PPh₂ gave rise to the formation of [Ph₂Sn(CH₂)_nSnPh₂(O₂PPh₂)](O₃SCF₃) (7-9; n = 1-3) and [Ph₂(OH)Sn(CH₂)_nSn(O₂PPh₂)Ph₂] (13-15; _n = 1-3), respectively. In the solid state, compounds 4-9 comprise ion pairs of cationic cyclo-[Ph₂SnCH₂SnPh₂(OH)]₂²⁺, cyclo-[Ph₂Sn(CH₂)_nSnPh₂(OH)]⁺ (n = 2, 3), and cyclo-[Ph₂Sn(CH₂)_nSnPh₂(O₂PPh₂)]⁺ (n = 1-3) and triflate anions. In MeCN, the eight-membered-ring system cyclo-[Ph₂SnCH₂SnPh₂(OH)]₂²⁺ appears to be in equilibrium with the four-membered-ring system cyclo-[Ph₂SnCH₂SnPh₂(OH)]⁺. In contrast, compounds 10-15 show no ionic character. Compounds 1-15 were characterized by multinuclear NMR spectroscopy in solution and in the solid state, IR spectroscopy, conductivity measurements, electrospray mass spectrometry, osmometric molecular weight determinations, and X-ray crystallography (4, 5, 7, and 12).

Preparation and characterisation of open-cell microporous nickel

In the present study, nickel foams with an open cell microporous structure were fabricated by the so-called space-holding particle sintering method, which included the adding of a particulate polymeric material (PMMA). The average pore size of the nickel foams approximated 10.5 μm; and the porosity ranged from 70 % to 80 %. The porous characteristics of the nickel foams were observed using scanning electron microscopy and the mechanical properties were evaluated using compressive tests. For comparison, nickel foams with an open-cell macroporous structure (pore size approximately 1.3 mm) were also presented. Results indicated that the nickel foams with a microporous structure possess enhanced mechanical properties than those with a macroporous structure.

Gel electrolytes based on lithium macro-anion salt

Montmorillonites are composed of aluminosilicate layers stacked one above the other, and the layer thickness is approximately 1 nm. In this work lithium modified montmorillonite (Li-MMT) was prepared and used as a lithium macro-anion salt in gel electrolytes. It was found that Li-MMT exhibited good compatibility with poly(ethylene glycol), DMSO and the ionic liquid, 1-ethyl-3-methylimidazolium dicyanamide (EMIdca), and a few of novel gel electrolytes based on Li-MMT were obtained. These gel electrolytes were investigated by X-ray powder diffraction, solid state NMR, conductivity measurements and cyclic voltammetry. High conductivities up to 10^{− 4} to 10^{− 3} S/cm at room temperature were observed with these macro-anion gel electrolytes. These gel materials were promising to be used as lithium conductive electrolytes in electrochemical devices, such as lithium batteries.

A Rasch analysis of the teachers music confidence scale

This article presents a new measure of teachers’ confidence to conduct musical activities with young children; Teachers Music Confidence Scale (TMCS). The TMCS was developed using a sample of 284 in-service and pre-service early childhood teachers in Hong Kong Special Administrative Region (HKSAR). The TMCS consisted of 10 musical activities. Teachers rated their confidence levels to conduct each activity on a scale from 1 (Not confident at all) to 5 (Very confident). An exploratory factor analysis retained a 10-item single factor that was replicated using confirmatory factor analysis procedures. All items of the TMCS fitted the Rasch model adequately. In-service teachers showed higher confidence levels to conduct several musical activities with young children than pre-service teachers. Implications of these findings for measuring teachers’ confidence to conduct musical activities with young children were discussed.

Mothers' AdvocateS In the Community (MOSAIC)- non-professional mentor support to reduce intimate partner violence and depression in mothers: a cluster randomised trial in primary care

Background : Effective interventions to increase safety and wellbeing of mothers experiencing intimate partner violence (IPV) are scarce. As much attention is focussed on professional intervention, this study aimed to determine the effectiveness of non-professional mentor support in reducing IPV and depression among pregnant and recent mothers experiencing, or at risk of IPV.

Methods : MOSAIC was a cluster randomised trial in 106 primary care (maternal and child health nurse and general practitioner) clinics in Melbourne, Australia. 63/106 clinics referred 215 eligible culturally and linguistically diverse women between January 2006 and December 2007. 167 in the intervention (I) arm, and 91 in the comparison (C) arm. 174 (80.9%) were recruited. 133 (76.4%) women (90 I and 43 C) completed follow-up at 12 months.

Intervention: 12 months of weekly home visiting from trained and supervised local mothers, (English & Vietnamese speaking) offering non-professional befriending, advocacy, parenting support and referrals.

Main outcome measures: Primary outcomes; IPV (Composite Abuse Scale CAS) and depression (Edinburgh Postnatal Depression Scale EPDS); secondary measures included wellbeing (SF-36), parenting stress (PSI-SF) and social support (MOS-SF) at baseline and follow-up.

Analysis: Intention-to-treat using multivariable logistic regression and propensity scoring.

Results : There was evidence of a true difference in mean abuse scores at follow-up in the intervention compared with the comparison arm (15.9 vs 21.8, AdjDiff -8.67, CI -16.2 to -1.15). There was weak evidence for other outcomes, but a trend was evident favouring the intervention: proportions of women with CAS scores ≥7, 51/88 (58.4%) vs 27/42 (64.3%) AdjOR 0.47, CI 0.21 to 1.05); depression (EPDS score ≥13) (19/85, 22% (I) vs 14/43, 33% (C); AdjOR 0.42, CI 0.17 to 1.06); physical wellbeing mean scores (PCS-SF36: AdjDiff 2.79; CI -0.40 to 5.99); mental wellbeing mean scores (MCS-SF36: AdjDiff 2.26; CI -1.48 to 6.00). There was no observed effect on parenting stress. 82% of women mentored would recommend mentors to friends in similar situations.

Conclusion : Non-professional mentor mother support appears promising for improving safety and enhancing physical and mental wellbeing among mothers experiencing intimate partner violence referred from primary care.

The effect of seed morphology on the potential dispersal of aquatic macrophytes by the common carp (Cyprinus carpio)

1. The potential for seed dispersal by fish (ichthyochory) will vary among aquatic plants because of differences in seed size and morphology.

2. To examine how seed morphology influences the probability of dispersal by the common carp (Cyprinus carpio), we studied seed ingestion, retention time and subsequent egestion and germination of seeds of Sparganium emersum and Sagittaria sagittifolia, two aquatic plant species with similar sized but morphologically different seeds.

3. We compared dispersal probabilities between the two plant species, in which the probability of dispersal is assumed to be a function of the probabilities of seed ingestion, egestion and germination, and the dispersal distance is assumed to be a function of seed egestion rate over time.

4. We found that, although the soft seeds of S. sagittifolia had an approximately 1.5 times higher probability of being ingested by the carp than the hard seeds of S. emersum (83.15% ± 1.8% versus 56.16% ± 2.7%, respectively), the latter had an almost twofold higher probability of surviving the passage through the digestive tract (38.58% ± 2.7% versus 20.97% ± 1.5%, respectively). Patterns of seed egestion over time did not differ between the two plant species, despite the difference in seed morphology. Gut passage had a different effect on seed germination between plant species. Compared with non-ingested controls, seeds of S. emersum showed a 12.6% increase in germination and a 2.1 day acceleration in germination rate, whereas seeds of S. sagittifolia displayed a 47.3% decrease and 5.1 day delay, respectively.

5. Our results suggest that seed morphology affects the dispersal probability and postdispersal establishment, but not the dispersal distance, of aquatic plants that are dispersed by fish.

Annual high-dose oral vitamin D and falls and fractures in older women : a randomized controlled trial

Context Improving vitamin D status may be an important modifiable risk factor to reduce falls and fractures; however, adherence to daily supplementation is typically poor.

Objective To determine whether a single annual dose of 500 000 IU of cholecalciferol administered orally to older women in autumn or winter would improve adherence and reduce the risk of falls and fracture.

Design, Setting, and Participants A double-blind, placebo-controlled trial of 2256 community-dwelling women, aged 70 years or older, considered to be at high risk of fracture were recruited from June 2003 to June 2005 and were randomly assigned to receive cholecalciferol or placebo each autumn to winter for 3 to 5 years. The study concluded in 2008.

Intervention 500 000 IU of cholecalciferol or placebo.

Main Outcome Measures Falls and fractures were ascertained using monthly calendars; details were confirmed by telephone interview. Fractures were radiologically confirmed. In a substudy, 137 randomly selected participants underwent serial blood sampling for 25-hydroxycholecalciferol and parathyroid hormone levels.

Results Women in the cholecalciferol (vitamin D) group had 171 fractures vs 135 in the placebo group; 837 women in the vitamin D group fell 2892 times (rate, 83.4 per 100 person-years) while 769 women in the placebo group fell 2512 times (rate, 72.7 per 100 person-years; incidence rate ratio [RR], 1.15; 95% confidence interval [CI], 1.02-1.30; P = .03). The incidence RR for fracture in the vitamin D group was 1.26 (95% CI, 1.00-1.59; P = .047) vs the placebo group (rates per 100 person-years, 4.9 vitamin D vs 3.9 placebo). A temporal pattern was observed in a post hoc analysis of falls. The incidence RR of falling in the vitamin D group vs the placebo group was 1.31 in the first 3 months after dosing and 1.13 during the following 9 months (test for homogeneity; P = .02). In the substudy, the median baseline serum 25-hydroxycholecalciferol was 49 nmol/L. Less than 3% of the substudy participants had 25-hydroxycholecalciferol levels lower than 25 nmol/L. In the vitamin D group, 25-hydroxycholecalciferol levels increased at 1 month after dosing to approximately 120 nmol/L, were approximately 90 nmol/L at 3 months, and remained higher than the placebo group 12 months after dosing.

Conclusion Among older community-dwelling women, annual oral administration of high-dose cholecalciferol resulted in an increased risk of falls and fractures.

Cause and effect in studies on unemployment, mental health and suicide: a meta-analytic and conceptual review

Background There are ongoing questions about whether unemployment has causal effects on suicide as this relationship may be confounded by past experiences of mental illness. The present review quantified the effects of adjustment for mental health on the relationship between unemployment and suicide. Findings were used to develop and interpret likely causal models of unemployment, mental health and suicide. Method A random-effects meta-analysis was conducted on five population-based cohort studies where temporal relationships could be clearly ascertained. Results Results of the meta-analysis showed that unemployment was associated with a significantly higher relative risk (RR) of suicide before adjustment for prior mental health [RR 1.58, 95% confidence interval (CI) 1.33–1.83]. After controlling for mental health, the RR of suicide following unemployment was reduced by approximately 37% (RR 1.15, 95% CI 1.00–1.30). Greater exposure to unemployment was associated with higher RR of suicide, and the pooled RR was higher for males than for females. Conclusions Plausible interpretations of likely pathways between unemployment and suicide are complex and difficult to validate given the poor delineation of associations over time and analytic rationale for confounder adjustment evident in the revised literature. Future research would be strengthened by explicit articulation of temporal relationships and causal assumptions. This would be complemented by longitudinal study designs suitable to assess potential confounders, mediators and effect modifiers influencing the relationship between unemployment and suicide.

Associations of diet quality with health-related quality of life in older Australian men and women

This study investigated associations between diet quality measures and quality of life two years later. Adults 55-65 years participating in the Wellbeing, Eating and Exercise for a Long Life (WELL) study in Victoria, Australia (n = 1150 men and n = 1307 women) completed a postal survey including a 111-item food frequency questionnaire in 2010. Diet quality in 2010 was assessed via the dietary guideline index (DGI), recommended food score (RFS) and Mediterranean diet score (MDS). The RAND 36-item survey assessed health-related quality of life in 2012. Associations were assessed using logistic regression adjusted for covariates. In men, DGI and RFS were associated with better reported energy (OR = 1.79, CI: 1.25, 2.55 and OR = 1.56, CI: 1.11, 2.19 respectively), and DGI was additionally associated with better general health (OR = 1.54, 95% CI: 1.08, 2.20), and overall mental component summary scale (OR = 1.51, CI: 1.07, 2.15) in the fully adjusted model. In women, associations between two indices of diet quality (DGI, RFS) physical function (OR = 1.66, CI: 1.19, 2.31 and OR = 1.70, CI: 1.21, 2.37 respectively) and general health (OR = 1.83, CI: 1.32, 2.54 and OR = 1.54, CI: 1.11, 2.14 respectively) were observed. DGI was also associated with overall physical component summary score (OR = 1.56, CI: 1.12, 2.17). Additional associations between emotional wellbeing and DGI (OR = 1.40, CI: 1.01, 1.93) and RFS (OR = 1.44, CI: 1.04, 1.99), and MDS and energy (OR = 1.53, CI: 1.11, 2.10) were observed in the fully adjusted model, in women only. Older adults with better quality diets report better health-related quality of life, with additional associations with emotional wellbeing observed in women.

Dynamic weight-bearing assessment of pain in knee osteoarthritis: a reliability and agreement study

Purpose: To evaluate the reliability, agreement and smallest detectable change in a measurement instrument for pain and function in knee osteoarthritis; the Dynamic weight-bearing Assessment of Pain (DAP). Methods: The sample size was set to 20 persons, recruited from the outpatient osteoarthritis clinic at Frederiksberg Hospital, Copenhagen. Two physiotherapists tested all participants during two visits; at the first visit, one single DAP (including four scores) was conducted by rater one; at the second visit, DAP was conducted by both raters one and two in randomized order with concealed allocation. The time interval was approximately 1.5 h. Measurement error was estimated by standard error of measurement (SEM). The intra- and inter-rater reliability was estimated by Intra-class Correlation Coefficients for agreement based on a two-way ANOVA with random effects (single measures ICC 2.1). Smallest detectable change (SDC) and limits of agreement were calculated.Results: The pain score showed excellent reliability in terms of ICC (intra-rater 0.93, CI 0.83–0.97, inter-rater 0.91, CI 0.78–0.96), low SEM (intra-rater 0.70, inter-rater 0.86, on a scale from 0 to 10), and acceptable SDC for intra-rater test (1.95). The three knee bend scores all had ICC above 0.50, showing fair-to-good reliability. None of the knee bend scores showed acceptable SEM and SDC. Conclusions: The reproducibility of the DAP pain score meets the demands for use in clinical practice and research. The total knee bend could be useful for motivational purpose in clinical use. Testing of other psychometric properties of the DAP is pending.

Validation of the Italian version of the Yale-Brown Obsessive Compulsive Scale-Second Edition (Y-BOCS-II) in a clinical sample

OBJECTIVE: The Yale-Brown Obsessive Compulsive Scale (Y-BOCS) is the most widely accepted measure of obsessive-compulsive disorder (OCD) symptom severity. Recently, the scale has been revised into a second edition (Y-BOCS-II) in order to improve its measurement properties. The present study aimed to evaluate the psychometric properties of the Italian version of the Y-BOCS-II Severity Scale (SS) in a large clinical sample. METHOD: The original version of the Y-BOCS-II was translated into Italian, which involved forward and back-translation procedures. The Italian Y-BOCS-II-SS was administered to one hundred twenty-five treatment-seeking adults with OCD, together with the original Y-BOCS-SS and a battery of self-report measures assessing OCD symptom severity and depressive and anxious symptomology. The factor structure, internal consistency, temporal stability, and construct validity were investigated on the whole sample, while inter-rater and test-retest reliability were assessed on a subsample of participants. RESULTS: Factor analyses revealed a two-factor structure different from those of the original scale, comprising (1) symptom severity; and (2) interference from symptoms. Internal consistency, test-retest reliability over a 2-week period and inter-rater reliability were satisfactory. The Y-BOCS-II-SS also showed excellent construct validity (and better than the Y-BOCS-SS), with good convergent and discriminant validity when assessed against other OCD symptom measures and measures of depression, anxiety and worry. CONCLUSIONS: These findings suggest that the Italian version of the Y-BOCS-II-SS retains the adequate psychometric properties of the original and that it can be confidently used as an assessment tool of OCD symptoms in both clinical and research settings.

Fusing data mining, machine learning and traditional statistics to detect biomarkers associated with depression

BACKGROUND: Atheoretical large-scale data mining techniques using machine learning algorithms have promise in the analysis of large epidemiological datasets. This study illustrates the use of a hybrid methodology for variable selection that took account of missing data and complex survey design to identify key biomarkers associated with depression from a large epidemiological study.

METHODS: The study used a three-step methodology amalgamating multiple imputation, a machine learning boosted regression algorithm and logistic regression, to identify key biomarkers associated with depression in the National Health and Nutrition Examination Study (2009-2010). Depression was measured using the Patient Health Questionnaire-9 and 67 biomarkers were analysed. Covariates in this study included gender, age, race, smoking, food security, Poverty Income Ratio, Body Mass Index, physical activity, alcohol use, medical conditions and medications. The final imputed weighted multiple logistic regression model included possible confounders and moderators.

RESULTS: After the creation of 20 imputation data sets from multiple chained regression sequences, machine learning boosted regression initially identified 21 biomarkers associated with depression. Using traditional logistic regression methods, including controlling for possible confounders and moderators, a final set of three biomarkers were selected. The final three biomarkers from the novel hybrid variable selection methodology were red cell distribution width (OR 1.15; 95% CI 1.01, 1.30), serum glucose (OR 1.01; 95% CI 1.00, 1.01) and total bilirubin (OR 0.12; 95% CI 0.05, 0.28). Significant interactions were found between total bilirubin with Mexican American/Hispanic group (p = 0.016), and current smokers (p<0.001).

CONCLUSION: The systematic use of a hybrid methodology for variable selection, fusing data mining techniques using a machine learning algorithm with traditional statistical modelling, accounted for missing data and complex survey sampling methodology and was demonstrated to be a useful tool for detecting three biomarkers associated with depression for future hypothesis generation: red cell distribution width, serum glucose and total bilirubin.