|Year : 2021 | Volume
| Issue : 4 | Page : 258-263
Delayed presentation to the urologist by men with lower urinary tract symptoms: The facts and figures from a hospital-based cross-sectional study
Eshiobo Irekpita1, Friday Ogbetere2, Abdullahi Abdulwahab-Ahmed3
1 Department of Surgery, Ambrose Alli University, Ekpoma, Nigeria
2 Department of Surgery, Edo University, Iyamho, Nigeria
3 Department of Surgery, Usmanu Danfodiyo University, Sokoto, Nigeria
|Date of Submission||25-Jun-2021|
|Date of Decision||01-Aug-2021|
|Date of Acceptance||27-Oct-2021|
|Date of Web Publication||07-Dec-2021|
Dr. Eshiobo Irekpita
Department of Surgery, Ambrose Alli University, Ekpoma
Source of Support: None, Conflict of Interest: None
Background: Men with lower urinary tract symptoms (LUTS) often present late. This work aims at studying the reasons for delayed presentation to the urologist by men with LUTS. Materials and Methods: This is a cross-sectional study. Delay was taken as 5 months of symptoms before consulting the urologist. The predictors assessed were age, occupation, education, number of children, number of brothers, number of wives, participants' location, and reason for delay. The outcome was the proportion of men with symptoms of more than 5 months and the correlation between predictors and outcome variables. Data were analyzed using International Business Machines–Statistical Programming for Social Sciences version 21. P value of 0.05 was taken as significant. Results: Three hundred and fifty-four men correctly filled the questionnaires. Finance (12.4%), belief symptoms were due to aging (18.4%), not knowing where to seek help (18.6%), and not knowing the diseases are treatable in the hospital (8.8%) were the reasons for delay. On linear regression analysis, only location (urban or rural) (P = 0.001) of the participants significantly predicted the reasons for delay, while on binary regression analysis, only the number of living brothers (P = 0.53) was close to predicting delay. Conclusion: Ignorance, poverty, culture, and beliefs are the factors that determine how long men delay before consulting the urologist.
Keywords: Beliefs, culture, delay, lower urinary tract symptoms, urologist
|How to cite this article:|
Irekpita E, Ogbetere F, Abdulwahab-Ahmed A. Delayed presentation to the urologist by men with lower urinary tract symptoms: The facts and figures from a hospital-based cross-sectional study. Curr Med Issues 2021;19:258-63
|How to cite this URL:|
Irekpita E, Ogbetere F, Abdulwahab-Ahmed A. Delayed presentation to the urologist by men with lower urinary tract symptoms: The facts and figures from a hospital-based cross-sectional study. Curr Med Issues [serial online] 2021 [cited 2022 Aug 12];19:258-63. Available from: https://www.cmijournal.org/text.asp?2021/19/4/258/331837
| Introduction|| |
Delay in presentation to the doctor following the occurrence of symptoms is a worldwide phenomenon though the extent and reasons for it vary. Patient delay refers to the period from the initial detection of symptoms and signs by the patient to the first medical consultation. In malignant diseases, this is usually considered to be 3 months. This experience is encountered in virtually all aspects of medical practice and specialty. For instance, Natalia and Usmanu in their study of gynecological malignancies in Kano documented a 63.54% patient delay in presentation. Osifo et al. recorded a 100% delay in patients with childhood abdominal tumors.
The extent of delay and the reasons adduced or documented for it vary with the disease and the region in which the study was done. In the developing world, lack of specialized, appropriately equipped units, cultural beliefs, reluctance to accept Western medicine, low economic status, and ignorance are some of the factors that lead to delay in patient presentation. This is remarkably different in developed countries. For instance, research conducted by the King's College London and University College London, revealed that embarrassment and patients not wanting to waste their doctors' time accounted for the delay found among women with breast cancer.
All these variables and their correlates are similar to what is seen in men with lower urinary tract symptoms (LUTS). According to McNeil and Hargreave, men with acute urinary retention often have LUTS for an average of 32 months prior to the incident. An international consensus conference identified LUTS to include symptoms relating to urinary storage and or voiding disturbances common among aging men. These symptoms are classified as voiding and storage LUTS and are most commonly due to benign prostatic hyperplasia.
LUTS are a common cause of presentation to the accident and emergency (A/E) and the urology clinic with a prevalence ranging from 15% to 61.2%. Delayed medical consultations often result in poor treatment outcome as a result of the presence of complications and a higher grade and stage of the causative disease. This work aims to study the reasons men with LUTS delay in presenting to the urologist.
| Materials and Methods|| |
This is a two-center, cross-sectional, hospital-based study of men with LUTS. However, the study was restricted to men with LUTS due to urological causes – benign prostatic hyperplasia, carcinoma of the prostate, prostatitis, urethral stricture, bladder tumor, and neurogenic disease, while those due to overactive bladder (for reasons of cost and availability of tools for diagnosis) and endocrine and other systemic disorders were excluded. All middle-aged and elderly men who met the inclusion criteria were included. Those who had difficulty understanding the questionnaire in spite of an interpreter or who refused to consent were excluded. Each participant was provided informed written consent before questionnaires were issued to them. Delay was taken as 3 months of symptoms before presentation to a first-level care provider and 5 months of symptoms before presentation to the urologist. A consecutive sampling method was used, having determined the sample size using a confidence interval of 95, error margin of 5, and a population base of 2,100,000 men in the two states. Following consent from the participants, the latter was given a quiet place to sit and fill the questionnaire and where required, a bilingual nurse interpreted the questionnaire to those who could not understand it. For the purpose of this study, the following guidelines were adopted: (1) all the local government headquarters were designated as urban centers, while the rest of the “;local government area was regarded” as rural; (2) all men employed in white-collar jobs were referred to as civil servants, in uniformed duties as military, engaged in peasant farming as farmers, retired from employment as pensioners, self-employed as businessmen, and then others; and (3) delay in presentation was taken as the presence of symptoms for up to 3 months before presentation to a first-level caregiver, while a delay in presentation to a urologist was set at 5 months. The participants were also categorized into those who presented before and after 3 months (Yes/No) and before and after 5 months (Yes/No) of symptoms. Participants who presented with urinary retention, bladder stones, urinary fistula, hydronephrosis/hydroureters, and a derailed creatinine were grouped as having complicated LUTS, while others were referred to as having simple LUTS. For the purpose of confidentiality, the patient's names were omitted from the questionnaire. Patients were informed that participation was voluntary and that they were free to withdraw from the study without any consequences.
The study adhered to the guidelines of the Declaration of Helsinki.
The study setting was the A/E and urology clinics of the hospitals, while the work took place between June 2017 and May 2019. The patients were either recruited at the point of entry at the A/E department or in the clinic, and records were updated until the final diagnosis was made.
The primary objective was to study the reasons men with LUTS present late to the urologist in our environment and to determine the extent of the problem.
The predictor variables assessed included age, occupation, educational status, awareness of available medical specialties, number of living children, number of living brothers, number of wives, provisional diagnosis, location of participants (urban or rural), patient's reason(s) for presenting late, and evidence of late presentation such as renal function impairment. Outcome variables assessed were mean duration of symptoms before presentation, and the proportion of men with symptom duration of more than 3 months and 5 months before presentation in BPH, carcinoma of the prostate, prostatitis, and urethral stricture and the proffered reason(s) for the delay and the association between the predictors and outcome variables.
The data were assembled in a pro forma designed for this study. Questionnaires in which the hospital number was not filled and those in which the duration of symptoms was not stated were rejected. The analysis was done using International Business Machines–the Statistical Package for Social Sciences for Windows (SPSS Inc. Released 2007, version 23.0. Armonk, New York, USA). P value of 0.05 or less was taken as significant. Linear regression analysis was used to determine the predictors for the reasons for delay, while binary regression analysis was used to determine the predictors of delay. Categorical variables were tested with Chi-square, while the Pearson correlation test was used for continuous variables. Mean, median, and mode were calculated where applicable. Charts and tables were used to depict the results.
| Results|| |
Following ethical approval, 365 men who met the inclusion criteria were selected for the study. However, 11 questionnaires (3.01%) were improperly filled and were therefore discarded. The peak age was in the seventh decade of life. The mean age was 66.87, standard deviation (SD): 14.06. The age distribution in decades was 40 years, 19 (5.4%); 41–50, 19 (5.4%); 51–60, 73 (20.6%); 61–70, 104 (29%); 71–80, 92 (26%); and above 80, 46 (13%).
The mean number of wives was 1.43 (SD: 0.70). All the participants were males. The mean number of brothers was 3.16 (SD: 4.52), while that of the number of living children was 8.37 (SD: 5.54). Two hundred and twenty-seven (64.1%) were rural dwellers, 124 (35.1) lived in urban areas, while there was no response from 3 (0.8%). [Figure 1] shows the educational level of participants.
|Figure 1: Distribution of participants according to educational level. PSLC: Primary School Leaving Certificate, WASC: West African School Certificate, OND: Ordinary National Diploma, HND: Higher National Diploma, University: University degree, None: No formal education, Others: Other forms of formal education.|
Click here to view
Out of the 354 participants, 200 (56.50%) were residents in southern Nigeria, while 154 (43.5%) were in the North. The mean duration of symptoms before presentation was 28.03 (SD: 35.27) months. [Figure 2] shows occupation of participants.
The provisional diagnosis was benign prostatic hyperplasia in 181 (51.1%), carcinoma of the prostate in 99 (28%), urethral stricture in 61 (17.2%), prostatitis in 4 (1.1%), bladder tumor in 2 (0.6%), and others 7 (2%). Of the 354 men, 186 (52.5%) presented with simple LUTS, while 168 (47.5%) had complicated LUTS. [Figure 3] shows the reasons for delay.
Sixteen (4.5%) of the participants first consulted a traditional medicine practitioner; 5 (1.4%) consulted a pharmacist; 5 (1.4%) were treated by a nurse, 142(48.6%) patronized a GP; and other types of practitioner: 14 (4%), while 142 (40.1%) had not.
The causes of delay in consulting the urologist were financial constraints (44, 12.4%); not knowing where to seek help (66, 18.6%); the belief that the symptoms were due to aging (65, 18.4); not knowing that LUTS is treatable in the hospital (31, 8.8%); too busy to seek help (4, 1.1%); belief that symptoms were due to aging/not knowing where to seek help 16 (4.5%); and others 114 (32.2%), while 14 (4.0%) did not respond. [Figure 4] shows the entry point of participants. Those grouped among “;others” included men whose delay was due to religious beliefs, fear of stigmatization, long distance from the hospital, and said to be an act of God.
The provisional diagnosis had a significant correlation (P = 0.034) with delay and with age (P < 0.001). The proportion of men who delayed was consistently higher in urethral stricture (90.16%) as against benign prostatic hyperplasia (83.46%) and carcinoma of the prostate (88.89%) when 3 months was used for analysis. This dropped slightly to 78.24% for BPH, 85.71% for carcinoma of the prostate, and 80.00% for urethral stricture at 5 months of symptoms. As the age of the participants increased, the proportion of men diagnosed primarily with carcinoma of the prostate increased, while that of benign prostatic hyperplasia, urethral stricture, and prostatitis decreased. The mode of presentation either with simple or complicated LUTS had no significant correlation with occupation (P = 0.159) and family setting (P = 0.547). The correlation with level of education (P = 0.001) was however significant, while that with location (urban or rural) was marginally so (P = 0.078). The proportion of men who presented with complicated LUTS decreased as the level of education increased. Similarly, as the duration of symptoms increased, complications occur and the proportion of men who presented in A/E increased.
Overall, 302 (85.30%) delayed in presenting to a first-level caregiver at 3 months, while 281 (79.9%) delayed in presenting to the urologist at 5 months. The type of intervention before presentation to the urologist had a significant correlation (P = 0.04) with the duration of symptoms before presentation, some participants were actually delayed by the first caregiver. The correlation with level of education (P = 0.113), age (P = 0.563), occupation (P = 0.495), and location (0.961) was not significant. One hundred and seventy-eight (89.00%) participants in the South delayed in presenting, while in the North, this was 125 (81.50%). Expectedly, the duration of symptoms before presentation had a significant correlation with serum creatinine at presentation (P = 0.000) in southern Nigeria, while the entry point had a significant correlation (P = 0.000) with the symptoms and signs at presentation. Expectedly too, more men with complicated LUTS presented in A/E, while those with simple LUTS were more likely to present at GOPD or were referred.
Linear regression analysis was done to determine the effect of the number of living brothers, the number of children, family setting, level of education, location of participants, age, and occupation on reasons for delayed presentation. The model gave an intermediate degree of correlation (R = 0.224, R2 = 0.078) and predicted the dependent variables significantly well (P = 0.029) (analysis of variance). The only predictor of the reasons for delay was location (urban or rural) of the participants (P = 0.001).
Furthermore, binary regression analysis was done to ascertain the effect of age, occupation, location, marital status, family setting, number of children, number of living brothers, and level of education on delay. The model explained 4.3% of the variance in delay at 5 months (Nagelkerke R2) and correctly classified 80.6%. The number of living brothers was closest to being significant (P = 0.053) [Table 1]. In other words, none was significant.
Of the 354 participants, 207 (58.50%) were aware that there are specialists in various fields. This had no significant correlation with age (P = 0.762) and delay (P = 0.535), while the correlation was significant with location (urban or rural) (P = 0.002), occupation (P = 0.004), and level of education of the participants (P = 0.000). The proportion of men who were aware increased as the educational level increased and among the urban dwellers.
| Discussion|| |
Delay in presenting to a doctor is a worldwide occurrence. The extent and causes however differ from one society to another depending on the level of development, culture, the disease in question, and societal prejudices about the disease. What is common to all is that delay leads to presentation with advanced-stage disease and a poorer treatment outcome. This is often the case with men who have carcinoma of the prostate, and who in this poor resource setting, commonly present with advanced disease. According to Knowles et al., in “;Great Britain, 30 children aged 1–15 years present annually for the first time with congenital adrenal hyperplasia. Older children frequently manifest prematurely advanced epiphyseal and pubertal maturation and genital virilization, which are often irreversible and likely to have long-lasting consequences for adult health and wellbeing.” This is reflected in this study which showed a strong association (P = 0.000) between the duration of symptoms and the serum creatinine level and a trend toward increasing creatinine level as the duration of symptoms increased.
Financial constraints are known worldwide to be a usual or common cause of delay in presenting to the doctor when men fall sick., Regional variations exist and this mostly depends on regional differences in culture, economy, and measures such as health insurance schemes put in place. The Nigerian Health Insurance Scheme is currently rudimentary, making out-of-pocket payment the norm. This explains why as many as 44 (12.4%) in this study gave financial constraints as their reason for delay in seeking help. This is however lower than the 39% reported by Ojewola et al. for LUTS in western Nigeria. Often, people with low socioeconomic status present with advanced-stage disease. The differences between the northern and southern parts of Nigeria in terms of financial access noted in this study are traceable to the differences between the two study centers used and the extent to which the nuclear family system has invaded the different regions of the country. While the study center in the South is semi-urban, that in the North is an urban state capital. Likewise, whereas the extended family system of being your brother's keeper is rapidly giving way to the nuclear family system in southern Nigeria, the former still remains common in the North.
Ignorance comes in different forms and with regard to health seeking habits, it may be demonstrated in the form of wrongly associating symptoms with aging, not knowing how and where to access care and in our environment, and the belief that certain diseases are only amenable to complementary and alternative medicine. Of these, not knowing where and how to access care was the most common ignorant behavior exhibited by participants (18.6%) in this study, followed closely by the assumption that the symptoms were due to aging (18.4%) and remotely, by the belief that the symptoms are not amenable to orthodox medicine (8.8%). The absence of a significant correlation between these causes and age (P = 0.060), level of education (P = 0.791), marital status (P = 0.717), family setting (polygamy or monogamy) (P = 0.414), number of children (P = 0.525), and number of living brothers (P = 0.459) using linear regression analysis is a reflection of the extent to which culture and beliefs deeply affect the health-care choices of these men irrespective of status. Binary regression analysis also demonstrated that only the number of living brothers (P = 0.053) marginally has a significant correlation with delay in presentation. Ojewola et al. however found a positive correlation with education and occupation in western Nigeria. Differences in culture and beliefs between the North and South of Nigeria account for the strong correlation between the causes of delay and the region of origin or residence of the participants [Table 1]. Similarly, the strong correlation between the causes of delay and location (urban or rural) stems from the inequitable distribution of wealth, health-care resources, family systems (nuclear or extended), and enlightenment programs between the urban and rural areas of the country.
These findings are in consonance with this author's work on self-reporting of erectile dysfunction and Olajide et al.'s work on urethral stricture. According to Olajide et al., diseases related to the genitalia or perineum are commonly associated with some level of stigma because of which sufferers are often unwilling to disclose or discuss them. This explains the absence of a significant correlation between the causes of delay and the number of living children (P = 0.525) and between causes of delay and number of living brothers (P = 0.459) using linear regression analysis. This implies that men are unlikely to discuss these afflictions with their wives, children, and brothers until complications occur and their relations discovered by themselves when consultation is already delayed. An overall delay of 79.9% at 5 months and 85.3% at 3 months in this study is similar to the findings by Ezeome (85%) in his study of delayed presentation by women with breast cancer in eastern Nigeria.
Authors have reported on various biological variables which may affect the duration of symptoms before presentation of which age is relevant to this study. Forbes et al. in their work on delay in breast cancer presentation reported “;no difference in frequency of delay by age or sex, although there was a trend suggesting that older people might be less likely to delay.” Age wise, their finding is similar to the finding in this study in which delay had no significant correlation with age (P = 0.104). Disease-related delays have also been documented. Khan et al. in their study of benign prostatic hyperplasia reported a delay of 78%, most of them presenting with urinary retention. In our study too, 78.24% presented after 5 months of clinical symptoms.
Many men with LUTS do not present for consultation as they do not perceive the symptoms as bothersome, a behavior which has been reported from many centers around the world.,, The mean duration of symptoms of 27.92 months reported in this study mostly indicates that participants lived with these symptoms for a long time and only presented when complications occurred or a deterioration in health was noticed by relation(s). This explains the large proportion of participants who presented in A/E (31.1%) and the large proportion that did so with complicated LUTS (41.8%). The proportion in this study with complicated LUTS is however lower than that reported from Pakistan in 2005, though this may have changed. The mean duration of symptoms is also lower than that of Ojewola et al. (40.8 months) and Olajide et al. (37 months) both from western Nigeria.
When participants were asked if they were aware of the availability of specialist doctors for their ailment, 58 percent responded in the affirmative, while 37.60% were not aware. There was no correlation between the level of awareness and age (P = 0.762) and delayed presentation (P = 0.535), whereas there was a trend toward increasing awareness with increasing education (P = 0.000), urban dwelling (P = 0.002), and occupation (P = 0.004). The effect of this increasing awareness was only seen on the mode of presentation and symptoms at presentation rather than on the duration of symptoms before presentation, again showcasing the effect of culture and beliefs on the participants. What this means is that to avoid embarrassment, urban men, educated men, and men with higher socioeconomic status more commonly present with simple LUTS though considerably delay in doing so.
| Conclusion|| |
Most men with LUTS present late to the first level health-care provider and the urologist. This behavior is undeterred by western education, occupation, and socioeconomic status because of culture, deeply rooted beliefs, and poverty. Inequitable distribution of health-care resources, widespread ignorance, and inadequate enlightenment of the general population combine to negatively influence health-care choices by men with LUTS. Reversing this situation region requires extensive community-based studies and massive enlightenment campaigns through the mass media, community extension work, sociocultural organizations, and religious bodies.
The limitation of this study is in the paucity of literature specifically addressing delayed presentation by men with LUTS, hence our choice of 5 months as the time frame for delayed presentation to the urologist. Most references were drawn from breast cancer studies. Its strength lies in the sample size, detailed information base, the heterogeneous study population, and coverage. These are enough to allow for generalization of the findings to the Nigerian population.
Research quality and ethics statement
All authors of this manuscript declare that this scientific study is in compliance with standard reporting guidelines set forth by the EQUATOR Network. The authors ratify that this study required Institutional Review Board/Ethics Committee review, and hence, prior approval was obtained from Usmanu Danfodiyo University Teaching Hospital IRB Min. No. HREC NO: ISTH/HREC/2015/NOVEMBER/016 and UDUTH/HREC/2015/No. 41 dated 16 Nov 2015). We also declare that we did not plagiarize the contents of this manuscript and have performed a Plagiarism Check.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
| References|| |
Zohreh K, Ali T, Robab LR, Eesa M, Ramesh O. Delayed presentation of self discovered breast cancer symptoms in Iranian women: A quantitative study. Asian Pac J Cancer Prev 2014;15:9427-32.
Adamou N, Umar UA. Delayed Presentation of Patients with Gynaecological Malignancies in Kano, North-Western Nigeria. Open J Obstet Gynecol. 2015;5:333–40.
Osifo OD, Evbuonwan I, Efobi CA. Management of childhood abdominal masses by Nigerian traditional doctors: A worrisome cause of delayed presentation. Pak J Med Sci 2007;23:809-13.
Nureli WP, Khomapak M. Patient delay in consulting a medical doctor among Aceh women with breast cancer. Songklanagarind J Nurs 2014;34:1-11.
McNeill SA, Hargreave TB; Members of the Alfaur Study Group. Alfuzosin once daily facilitates return to voiding in patients in acute urinary retention. J Urol 2004;171:2316-20.
Abrams P, Chapple C, Khoury S, Roehrborn C, de la Rosette J; International Scientific Committee. Evaluation and treatment of LUTS in older men. J Urol 2009;181:1779-87.
Bock-Omma AA, Dienye PO, Oghu IS. Prevalence of LUTS suggestive of BPH in primary care, Port Harcourt, Nigeria. South Afr Fam Pract 2013;55:467-72.
Arndt V, Stürmer T, Stegmaier C, Ziegler H, Dhom G, Brenner H. Patient delay and stage of diagnosis among breast cancer patients in Germany – A population based study. Br J Cancer 2002;86:1034-40.
Irekpita E, Owobu C, Aigbe E, Obasikene G, Igbe A. Assessment of DRE and PSA as diagnostic and screening tools for carcinoma of the prostate in rural Nigeria. East Cent Afr J Surg 2014;19:53.
Knowles RL, Khalid MJ, Oerton MJ, Hindmarsh PC, Kelnar CJ, Dezateux C. Late clinical presentation of congenital adrenal hyperplasia in older children: Findings from national pediatric surveillance. Arch Dis Child 2014;99:30-4.
Gulzar F, Akhtar MS, Sadiq R, Bashir S, Jamil S, Baig SM. Identifying the reasons for delayed presentation of Pakistani breast cancer patients at a tertiary care hospital. Cancer Manag Res 2019;11:1087-96.
Ojewola RW, Oridota ES, Balogun OS, Ogundare EO, Alabi TO. Lower urinary tract symptoms: Prevalence, Perceptions, and healthcare-seeking behavior amongst Nigerian men. World J Mens Health 2016;34:200-8.
Rachet B, Ellis L, Maringe C, Chu T, Nur U, Quaresma M, et al.
Socioeconomic inequalities in cancer survival in England after the NHS cancer plan. Br J Cancer 2010;103:446-53.
Falaki FA, Grema BA, Singh S, Jega RM, Kaoje A, Arisegi SA. Family functionality among elderly patients with chronic illnesses attending the general outpatient clinic of Usmanu Danfodiyo university teaching hospital, Sokoto, Nigeria. IAMMS 2019;1:36-43.
Irekpita E, Awe O, Salami T, Imomoh P, Oseni T. Clinical, cultural and psychosocial impediments to self reporting of erectile dysfunction by men in Edo state, Nigeria. Afr J Urol 2017;23:160-5.
Olajide AO, Olajide FO, Kolawole OA, Oseni I, Ajayi AI. A retrospective evaluation of challenges in urethral stricture management in a tertiary care centre of a poor resource community. Nephrourol Mon 2013;5:974-7.
Ezeome ER. Emmanuel. Delays in presentation and treatment of breast cancer in Enugu, Nigeria. Niger J Clin Pract 2010;13:311-6.
] [Full text]
Forbes LJ, Warburton F, Richards MA, Ramirez AJ. Risk factors for delay in symptomatic presentation: A survey of cancer patients. Br J Cancer 2014;111:581-8.
Khan M, Khan AL, Khan S, Nawaz H. Benign prostatic hyperplasia: Mode of presentation and postoperative outcome. J Pak Med Assoc 2005;55:20-3.
Lee EH, Chun KH, Lee Y. Benign prostatic hyperplasia in community-dwelling elderly in Korea. Taehan Kanho Hakhoe Chi 2005;35:1508-13.
Hunter DJ, Berra-Unamuno A. Treatment-seeking behaviour and stated preferences for prostatectomy in Spanish men with lower urinary tract symptoms. Br J Urol 1997;79:742-8.
[Figure 1], [Figure 2], [Figure 3], [Figure 4]