Key Risk-Factors Contributing to Cardiovascular Disease: Lifestyle Modifications to Improve Cardiovascular Health

  • Home
  • Key Risk-Factors Contributing to Cardiovascular Disease: Lifestyle Modifications to Improve Cardiovascular Health

Key Risk-Factors Contributing to Cardiovascular Disease: Lifestyle Modifications to Improve Cardiovascular Health

1Ejiofor Augustine Ezika Ph.D, 2Adaobi Nwankwo-Ezika MBSS, 3Chibuzor Roselyn Ezendiokwelle Ph.D, 4John Obeng PhD, 5Bolanle Ola PhD
1School of Health and Life sciences, University of the West of Scotland, UK
2Family medicine, Isle of Wight NHS Trust, UK
3Department of Social Work, University of East London, UK
4School of Health and Society, University of Salford, UK
5Institute of Digital Health Care, University of Warwick, UK



ABSTRACT:

Cardiovascular disease is a preventable public health issue. The aim of this review is to identify modifiable risk-factors for cardiovascular disease and recommend lifestyle modification to prevent cardiovascular disease. PubMed, ScienceDirect, SAGE, Google Scholar, World Health Organisation websites, as well as public and community health textbooks, were hand searched and academic resources which are relevant for this review were selected for inclusion. Cardiovascular disease is leading cause of deaths in all continents of the world. While deaths from cardiovascular disease is increasing in Africa and Asia, it is decreasing in Australia and fluctuating in the USA. Premature deaths from cardiovascular disease are preeminent across middle income countries in Europe compared with high income countries. Cardiovascular disease is higher in rural areas of South America compared with urban areas. Trends in lifestyle patterns, including physical inactivity, smoking behaviour, and diets contribute to cardiovascular disease-prone conditions. Prevention includes health promotion activities that facilitate healthy living across life course and limit the initial onset of cardiovascular disease. Investment in prevention is the critical sustainable solution for the cardiovascular disease epidemic. Adopting WHO existing policies within individual countries in Africa, Asia, and middle-income countries in Europe, and ensuring robust implementation of such policies across life course and from different layers of sectors such as education and workplaces would have wider impacts in reducing risk and cardiovascular disease burden in the respective continents. Government of countries with worsening cardiovascular events should also increase health financing and focus on strengthening primary health care services for prevention and treatment of cardiovascular disease.

 

KEYWORDS:

cardiovascular disease prevention, tobacco use, physical activity, nutrition, metabolic syndrome

 

REFERENCES :

1) Adegoke, O., A., Adedoyin, R., A., Balogun, M., O., Adebayo, R., A., Bisiriyu, L., A. and Salawu, A., A. (2010) Prevalence of metabolic syndrome in a rural community in Nigeria. Metabolic Syndrome and Related Disorders, Vol. 8 (1), pp.59-62
2) Al-Nakeeb, Y., Duncan, M., J., Lyons, M. and Woodfield, L. (2007) Body fatness and physical activity levels of young children. Annals of Human Biology, 34, 1-12
3) Aune, D., Giovannucci, E., Boffetta, P., Fadnes, L., T., Keum, N., Norat, T., Greenwood, D., C., Elio Riboli, E., Lars J Vatten, L., J., and Tonstad, S. (2017) Fruit and vegetable intake and the risk of cardiovascular disease, total cancer and all-cause mortality—a systematic review and dose-response meta-analysis of prospective studies. International Journal of Epidemiology, 46 (3), 1029–1056
4) Avery, L, Flynn, D., Trenell, M (2012) Changing physical activity behaviour in type 2 diabetes. Diabetes Care, 35 (12), 281 – 2689
5) Balkau, B., Charles, M., A. (1999) Comment on the provisional report from the WHO consultation European Group for the Study of Insulin Resistance (EGIR) Diabetic Medicine, 16, 442–3
6) Barnoya, J., Glantz, S. (2005) Cardiovascular effects of second-hand smoke: nearly as large as smoking. Circulation, 111 (20), 2684 98
7) Benatti, P., Peluso, G., Nicolai, R. and Calvani, M. (2004) Polyunsaturated fatty acids: biochemical, nutritional and epigenetic properties. Journal of the American College of Nutrition, 4, 281-302 
8) Boffetta, P. and Straif, K. (2009) Use of smokeless tobacco and risk of myocardial infarction and stroke: systematic review with meta-analysis. British Medical Journal, 339, 1136
9) Bradbury, J., C. and Hilleman, D. E. (2013) Overview of omega-3 fatty acid therapies. Pharmacy and therapeutics, 38 (11), 681 – 690
10) Brown, I., J., Tzoulaki, I., Candeias, V. and Elliott, P. (2009) Salt intakes around the world: implications for public health. International Journal of Epidemiology, 38, 791-813
11) Buttar, H., S., Li, T., Ravi, N (2005) Prevention of cardiovascular disease: Role of exercise, dietary interventions, obesity and smoking cessation. Experimental and Clinical Cardiology, 10 (4), 229 – 249
12) Clarke, J., Herzberg, G., Peeling, J., Buist, R., Corbett, D. (2005) Dietary supplementation of omega-3 polyunsaturated fatty acids worsens forelimb motor function after intracerebral hemorrhage in rats. Experimental Neurology, 191(1):119-27.
13) Collins, A., E., Pakiz, B., Rock, G., L. (2008) Factors associated with obesity in Indonesian adolescents. International Journal of Paediatrics Obesity, 3, 58-64
14) Cook, N., R., Cutter, J., A., Obarzanek, E., Burning, J., E., Rrxrode, K., M., Kumanyika, S., Appel., L., J., and Whelton, P, K. (2007) Long term effects of dietary sodium reduction on cardiovascular disease outcomes: observational follow-up of the trials of hypertension prevention (TOHP) British Medical Journal, 334, 1-8
15) Cronin, P., Ryan, F., Coughlan., M. (2007) Undertaking a literature review: a step-by-step approach. British Journal of Nursing, 17 (1), 38 – 43
16) Djousséa, L., Akinkuolieb, J., A, O., Wu, H., Y., Eric, L., Dingg, L., and Gazianoa, M., J. (2012) Fish consumption, omega-3 fatty acids and risk of heart failure: a meta-analysis. Clinical Nutrition, 31 6), pp. 846–853
17) Einhorn D., Reaven, G., M., Cobin, R., H., Ford, E., Ganda, O., P., Handelsman (2003) American College of Endocrinology position statement on the insulin resistance syndrome. Endocrinology Practice, 9, 237–52
18) Ekinci, E., I., Clarke, S., Thomas, M., C, Moran, J., L., Cheong, K., MacIsaac, R., J., and Jerums, G (2011) Dietary salt intake and mortality in patients with type 2 diabetes. Diabetes, 34, 703-709
19) Emily, S., Ulrika, E., Bo, G., Kerstin, S., Hakan, O. and Elsabet, W. (2008) Do both heterocyclic amines and omega-6 polyunsaturated fatty acids contribute to the incidence of breast cancer in postmenopausal women of the Malmo diet and cancer cohort? International Journal of Cancer, 123 (7), 1637-1643
20) Ezika, A, E (2021) cardiovascular disease prevention; impacts of an intervention on clinical practice. Journal of Medical Science and Clinical Research, 09 (05), 60 – 71
21) Ezika, A., E., Nwankwo-Ezika, A (2020) Transtheoretical model as a framework for promoting cardiovascular health through behaviour change: a systematic review. International Research Journal of Public Health, 4 (46), 1 – 11
22) Feldeisen, S., E., Tucker, K., L. (2007) Nutritional strategies in the prevention and treatment of metabolic syndrome. Applied Physiology, Nutrition, and Metabolism, 32 (1), 191-198
23) Fischer, F. and Kraemer, A. (2015) Meta-analysis of the association between second-hand smoke exposure and ischaemic heart disease, COPD and stroke. BMC Public Health, 15, 2 – 18
24) Foster, G., D., Wyatt, H., R., Hill, J., O., McGuckin, B., G., Brill, C., Mohammed, B., S., Szapary, P., O, Rader, D., J., Edman, J., S., and Klein, S. (2003) Randomised trial of a low-carbohydrate diet for obesity. New England Journal of Medicine, 348, 2082 – 2090
25) Galassi A, Reynolds K, He J (2006) Metabolic syndrome and risk of cardiovascular disease: a meta-analysis. American Journal of Medicine, 119(10), pp. 812-9.
26) Golbidi, S., and Laher, I. (2012) Exercise and the cardiovascular system. Cardiology Research and Practice, 21 (2), 135-145
27) Hackshaw, A., Morris, J., K., Boniface, S., Tang, J., Milenkovic, D. (2017) Low cigarette consumption and risk of coronary heart disease and stroke: meta-analysis of 141 cohort studies in 55 study reports. British Medical Journal, 360, 1-13
28) Haidich (2010) Meta-analysis in medical research. Hippokratia, 14 (1), 29 – 37
29) Hannan, A., L., Hing, W., Simas, V., Climstein, M., Coombes, J., Jayasinghe, R., Byrnes, J, and Furness, J. (2018) High-intensity interval training versus moderate intensity continuous training within cardiac rehabilitation: a systematic review and meta-analysis. Journal of Sports Medicine, 9, 1 – 7
30) He, F., J., MacGregor, G., A (2002) Effect of modest salt reduction on blood pressure: a meta-analysis of randomised trials. Implications for public health. Journal of Human Biology, 16, 761 – 770
31) He, F., J., MacGregor (2008) A comprehensive review of salt and health and current experience of world salt reduction programmes. Journal of Human Hypertension, 23, 363 – 384
32) Holub, D., J. and Holub, B., J. (2004) Omega-3 fatty acids from fish oils and cardiovascular disease. Molecular and Cellular Biochemistry, 263 (1), 217 – 225
33) Hou, L., Li, F., Wang, Y., Ou, Z., Xu, D., Tan, W., Dai, M. (2015) Association between dietary patterns and coronary heart disease: a meta-analysis of prospective cohort studies. International Journal of Clinical and Experimental Medicine, 8 (1), pp. 781 – 790
34) Hung, H., Joshipura, K., J., Jiang, R., Hu, F., B., Hunter, D., Smith-warner, S., Colditz, G., A., Rosner, B., Spiegelman, D. and Willett, W., C. (2004) Fruit and vegetable intake and risks of major chronic disease. Journal of National Cancer Institute, 96 (2), 1577 – 1584
35) International Diabetic Federation (2012) Metabolic syndrome in children and adolescents. https://idf.org/media/uploads/2023/05/attachments-31.pdf
36) Jaramillo, P., L., Joseph, P., Lopez, J., P., Lanas, F., Avezum, A., Diaz, R., Camacho, P., Seron, P., Oliveira, G (2022) Risk-factors, cardiovascular disease, and mortality in South Africa: a pure sub study. European Heart Journal, 43 (30), 2841 – 2851
37) Katzmarzyk, P., T., Church, T., S., Craig, C., L., and Bouchard, C. (2009) Sitting times and mortality from all causes, cardiovascular disease, and cancer. Medicine & Science in Sports &Exercise, 41, 998-1005
38) Keafes, A., K., Mocumbi, A., O., Ntsekhe, M., Sliwa, K., Stewart, M (2017) cardiovascular disease in Africa: epidemiological profile and challenges. Nature Reviews Cardiology, 14, 273–293
39) Laaksonen, D., E., Nyyssonen, K., Niskanen, L., Rissanen, T., H., and Salonen, J., T. (2005) Prediction of cardiovascular mortality in middle-aged men by dietary and serum linoleic polyunsaturated fatty acids. Archives of Internal Medicine, I65 (2), 193-199
40) Lackland, D., T, Roccella, E., J, Deutsch, A., F, Fornage, M, George, M., G, Howard, G, Kissela, B.,M, Kittner S.,J, Lichtman, J., H, Lisabeth, LD, (2014) on behalf of the American Heart Association Stroke Council; Council on Cardiovascular and Stroke Nursing; Council on Quality of Care and Outcomes Research; Council on Functional Genomics and Translational Biology. Factors influencing the decline in stroke mortality: a statement from the American Heart Association/American Stroke Association. Stroke, 45, 315–353.
41) Laforgia P., L, Auguadro C, Bronzato S., Durante A. (2022) the reduction of mortality in acute myocardial infarction: from bed rest to future directions. International Journal of Preventive Medicine,13, 56.
42) Li and Siegrist (2012) Physical Activity and Risk of Cardiovascular Disease—A Meta-Analysis of Prospective Cohort Studies. International Journal of Environmental Research, 9, 391 – 407
43) Loeffelholz, C., O, and Birkenfeld, A. Non-Exercise activity thermogenesis-it’s NEAT (2022) Available from: Non-Exercise Activity Thermogenesis in Human Energy Homeostasis – Endotext – NCBI Bookshelf (nih.gov)
44) Mahfouz, A., A., Abdelmoneim, I., Khan, M., Y., Daffalla, A., A., Diab, M., M., Al-Gelban, K., S., Moussa, H. (2008) Obesity and related behaviours among adolescent schoolboys, Abha city, south western Saudi Arabia. Journal of Tropical Paediatrics, 54 (2), 120-124
45) Malik, V., S., Popkin, B., M., Bray, G., A., Despres, J., Hu, F., B (2010) Sugar-sweetened beverages, obesity, type 2 diabetes mellitus, and cardiovascular risk. Circulation, 121, pp. 1356 – 1364
46) Martin, S., S., Aday, A., W., Almarzooq, Z., A., Anderson, C., A., M., Arora, P., Avert, C., L (2024a) 2024 heart disease and stroke statistics: a report of US and global data from the American heart association. Circulation, 144 (8), 347 – 913
47) Martin S., S, Aday A., W, Almarzooq Z., I, Anderson C., A., M., Arora P., Avery C., L, Baker-Smith C., M, Barone G., B, Beaton A., Z, Boehme AK, (2024b) on behalf of the American Heart Association Council on Epidemiology and Prevention Statistics Committee and Stroke Statistics Subcommittee. Heart disease and stroke statistics: a report of US and global data from the American Heart Association. Circulation, 49, 312–913.
48) Meckling, K, A, and Sherfey, R. (2007) A randomised trial of a hypocaloric high-protein diet, with and without exercise, on weight loss, fitness, and markers of the metabolic syndrome in overweight and obese women. Applied Physiology, Nutrition and Metabolism, 32 (4), 743-752
49) Mensah, G., A., Sampson, Uchechukwu, K., A., Roth, G., A., Forouzanfar, M., H., Naghavi, M., Murray, C., Moran, A., E., Feigin, V., L (2015) Mortality from cardiovascular diseases in sub-Saharan Africa, 1990-2013: a systematic analysis of data from the Global Burden of Disease Study 2013. Cardiovascular Journal of Africa, 26, 6–10
50) Minja, N., W., Nakagaayi, D., Aliku, T., Zhang, W., SSinabulya, I., Nabaale, J., Amutuhaire, W., Loizaga, S., Nagire, E., Rwebembera, J., Okeilo, E., Kayima, J. (2022) Cardiovascular diseases in Africa in the twenty-first century: gaps and priorities going forward. Frontiers in Cardiovascular Medicine, 10, 1 – 20
51) Mitch, W., E. (2005) Beneficial responses to modified diets in treating patients with chronic kidney disease. Kidney International Supplements, 94, 133-135
52) Mons, U., Müezzinler, A., Gellert, C., Schöttker, B., Abnet, C., C., Bobak, M., Groot, L., Freedman, N., D., Jansen, E., Kee, F., Kromhout, D., Kuulasmaa, K., Laatikainen, T., O’Doherty, M., G., Bueno-de-Mesquita,, B, Orfanos, P., Peters, A., Schouw, Y., T., Wilsgaard, T., Wolk, A., Trichopoulou, A., Boffetta, P., Brenner, H. (2015) Impact of smoking and smoking cessation on cardiovascular events and mortality among older adults: meta-analysis of individual participant data from prospective cohort studies of the CHANCES consortium. British Medical Journal, 350, pp. 1 -11
53) Mosca, L., Appel, L., J., Benjamin, E., J., Berra, K., Chandra-Strobos, N., Fabunmi, R., Grady, D., Haan, C., K, Hayes, S., N., Judelson, D., R., Keenan, N., L., McBride, P.., Oparil, S., Ouyang, P., Oz, M., C., Mendelssohn, M., E., Pasternak, R., C., Pinn, U., W., Robertson, R., M., Schenck-Gustafsson, K., Sila, C., A., Smith, S.,C Sopko, G., Taylor, A., L., Walsh, B.,W., Wenger, N.,K. and Williams, C., L. (2004) Evidence-based guidelines for cardiovascular disease prevention. Circulation Vol.109, pp.672-693
54) National Institute for Health and Care Excellence (2023) What is CVD? Definition of CVD | Background information | CVD risk assessment and management | CKS | NICE
55) Oono, I., P., Mackay, D., F., Pell, J., P. (2011) Meta-analysis of the association between second-hand smoke exposure and stroke. Public Health, 33 (4), pp. 496–502
56) Ortega, F., B., Ruiz, J., R., and Sjostrom, M. (2007) Physical activity, overweight and central adiposity in Swedish children and adolescents: the European youth heart study. International Journal of Behavioural Nutrition and Physical Activity, 4, (61), 1-24
57) Owen, N., Sparling, P., E., and Mathews, C., E. (2010) Sedentary behaviour: emerging evidence for new health risk. Mayo Clinic Proceedings, 85 (12), 1138-1141
58) Owolabi TOS, Ezika EA, Lewitt M, Cross B. (2016) Communication media and cardiovascular health promotion as factors for sustainable development in Nigeria. Journal of Sustainable Development in Africa, 18(1): 156 – 172.
59) Paterna, S., Gaspare, P., Fasullo, S., Sarullo, F., M., and Di Pasquale, P. (2008) Normal-sodium diet compared with low-sodium diet in compensated cognitive heart failure: is sodium an old enemy or a new friend? Clinical Science, 114, 221-230
60) Paterna, S., Parrinello, G., Cannizzaro, S., Fasulo, S., Torres, D., Sarullo, F., M., and Di Pasquale, P. (2009) Medium term effects of different dosage of diuretic, and fluid administration on neuro- hormonal and clinical outcome in patients with recently compensated heart failure. American Journal of Cardiology, 103, 93-102
61) Peng, Y., Wang, Z (2018) Cardiovascular health status among Australian adults. Clinical Epidemiology, 10, 167 – 178
62) Piano, M., R., Benowitz, N., L., FitzGerald, G., A., Coatbridge, S., Heath, J., Hahn, E., Pechalek, T., F., and Howard, J. (2010) Impact of smokeless tobacco products on cardiovascular disease: implications for policy, prevention, and treatment. Circulation, 122, 1520-1544
63) Planinsec, J., and Matejek, C. (2004) Differences in physical activity between non-overweight and obese children. Collegiums Antropologicum, 28, 747-754
64) Prasad, D. S., Das, B., C., (2009) Physical inactivity, a cardiovascular risk factor. Indian Journal of Medical Science, 63 (1), pp. 33 – 42
65) Rakesh, M., P. and Viswanathan, M. (2012) Changing definitions of metabolic syndrome. Indian Journal of Endocrinology and Metabolism, Vol.16 (1), pp. 7 – 12
66) Roth, G., A., Mensah, G., A., Johnson, G., O., Addolorato, G (2020) Global burden of cardiovascular disease and risk-factors, 1990 – 2019. Journal of the American College of Cardiology, 76 (25), 2982 – 3021
67) Schuit, A, J, Van Loon J., M., Tijhuis, M, Ocke, M., C. (2002) Clustering of lifestyle risk factors in a general adult population. Preventive Medicine, 35, 219-224
68) Satoh, K., Satoh, T., Yaoita, N., Shimokawa, H (2019) Recent Advances in the understanding of thrombosis. Arteriosclerosis, Thrombosis, and Vascular Biology, 39 (6), 1 – 11
69) Sattelmair, J., Pertman, J., Ding, E., L., Kohl, H., W., Haskell, W., and Lee. I (2011) Dose response between physical activity and risk of coronary heart disease: a meta-analysis. Circulation, 124 (7), pp. 789 – 795
70) Sebanjo, O. and Oshikoya, K., A. (2010) Physical activity and body mass index of school children and adolescents in Abeokuta, southwest Nigeria. World Journal of Paediatrics, 6 (3), pp. 217-222
71) Strazzulo, P., D’Elia, L., Kandala, N., B., and Cappuccio, F., P. (2009) Salt intake, stroke, and cardiovascular disease: meta-analysis of prospective studies. British Medical Journal, 339, 4567
72) Thomas, M., C., Moran, J., Forsblom, C., Hargutsalo, V., Thorn, L., Ahola, A., Waden, J., Tolonen, N., Sarahelmo, M., Gordin, D., Groop, P., H., Diane, F.and Study Group (2011) The association between dietary sodium intake, ESRD, and all-cause mortality in patients with type 1 diabetes. Diabetes Care, 34, 861-866
73) Thomson, C., A., Ravia, J. (2011) A systematic review of behavioural interventions to promote intake of fruit and vegetables. Journal of American Diet Association, 111, 1523 – 1535
74) Teo, K., K., Ounpuu S., Hawken, S., Pandey, M., R., Valentin, V., Hunt, D., Diaz, R., Rashed, W., Freeman, R., Jiang, L., Zhang., X, Yusuf, S., INTERHEART Study Investigators (2006) Tobacco use and risk of myocardial infarction in 52 countries in the INTERHEART study: a case-control study. Lancet, 368, 647– 658.
75) Thompson, A., M., Campagna, P., D., Rehman, L., A., Murphy, R., J., Rasmussen, R., L. and Ness, G., W. (2005) Physical activity and body mass index in grade 3, 7, and II Nova Scotia students. Medicine & Science in Sports & Exercise, 37 (11), 1902-1908
76) Timmis, A., Vardas, P., Townsend, N., Torbica, A., Katus, H., Smedt, D., Gale, C., P., Maggioni, A., P (2022) European Society of cardiology: cardiovascular disease statistics 2021. European Heart Journal, 8 (43), 716 – 799
77) Vandelanotte, C., De Bourdeaudhuij I., Sallis, J., F., Spittaels, H., Brug, J. (2005) Efficacy of sequential and simultaneous interactive computer tailored interventions for increasing physical activity and decreasing fat intake. Annals of Behavioural Medicine, 29, 138-146.
78) Vona, A., Rossi, P., Capodaglio, P., Rizzo, S., Servi, P., De Marchi, M. and Cobeli, F. (2004) Impact of physical training and detraining on endothelium-dependent vasodilation in patients with recent acute myocardial infarction. American Heart Journal, 147 (6), 1039-1046
79) Wang, X., Ouyang Y., Liu, J., Zhu, M., Zhao, G., Bao, W., Hu, F., B (2014) Fruit and vegetable consumption and mortality from all causes, cardiovascular disease, and cancer: systematic review and dose-response meta-analysis of prospective cohort studies. British Medical Journal, 349, 1 – 14
80) Warburton, D., E., R, Nicol C., W, and Bredin, S., S., D. Health benefits of physical activity: the evidence. Canadian Medical Association Journal 2006; 174 (6): 801 – 809
81) Waters, A., Trinh, L., Chau, T., Bourchier, M., Moon, L (2003) Latest statistics on cardiovascular disease in Australia. Clinical and Experimental Pharmacology and Physiology, 40 (6), 347 – 356
82) World Health Organization. (‎1999)‎. Definition, diagnosis and classification of diabetes mellitus and its complications: report of a WHO consultation. Part 1, Diagnosis and classification of diabetes mellitus. World Health Organization. WHO_NCD_NCS_99.2.pdf
83) WHO (2007a) Prevention of cardiovascular disease: guidelines for assessment and management of cardiovascular risk. DocHdl1tmpTarget (who.int)
84) WHO (2007b) Prevention of cardiovascular disease: pocket guidelines for assessment and management of cardiovascular risk. Prevention of Cardiovascular Disease. Pocket Guidelines for Assessment and … – World Health Organization – Google Books
85) WHO (2010a) Global recommendations on physical activity for health. Available from: Global recommendations on physical activity for health (who.int)
86) WHO (2010b) Creating an enabling environment for population-based salt reduction strategies: report of a joint technical meeting held by WHO and food standards agency, United Kingdom, July 2010. 9789241500777_eng.pdf (who.int)
87) WHO (2009) Physical activity for children and young people. Available from: Recommendations | Physical activity for children and young people | Guidance | NICE
88) WHO (2021) cardiovascular diseases (CVDs) cardiovascular diseases (CVDs) (who.int)
89) Williamson, D., F., Vinicor, F., Bowman, B., A. (2004) Primary prevention of type 2 diabetes mellitus by lifestyle intervention: implications for health policy. Annals of Internal Medicine, 140, 951 – 957
90) Zhao, D (2021) Epidemiological features of cardiovascular disease in Asia. Journal of American College of Cardiology, 1 (1), 1 – 13

  • Share

Leave a Reply

Your email address will not be published. Required fields are marked *