Research proposal.

Research hypothesis-

Obesity is an excessive fat accumulation which most commonly builds up around the abdomen. (Ofei, 2005) Defects in the abdomen such as a protrusion of abdominal organs or fatty tissue through the inguinal canal produce inguinal hernias.  An in-depth analysis and comparison of two studies support the theory that obesity increases the recurrence rate of inguinal hernias. (Y El-Dhuwaib et al., 2012) (Froylich et al., 2016) Due to a range of limitations, the results obtained may be invalid leading to an incorrect interpretation. Further testing and avoidance of invalid methods can either allow the hypothesis to be supported or refuted. The hypothesis states that the success rate of inguinal hernia repair is lower in obese patients because increased surgical and post-operative complications contribute to a higher recurrence rate.

Aims and objective-

To identify surgical complications and postoperative problems that arose in non-obese and obese patients.

To identify the amount of recurrences throughout a 5 year time scale in, non-obese and obese patients.

To identify and compare the recurrence rate of inguinal hernia in, non-obese and obese patients.

Study proposal

Previous studies

Within the study performed by Y El-Dhuwaib on inguinal hernia repair surgery in non-obese patients, accuracy was ensured by using HES (hospital episode statistics) from the NHS information centre to review the patients. (Y El-Dhuwaib et al., 2012) This method is effective in preventing ethics or possible dishonest information as by using hospital records rather than patients own responses, results are more reliable. (Stiender, 2010) After this patients were spilt into categories based on whether their ICD codes matched so that patients with irrelevant conditions could be eliminated from the analysis.  Also they were categorized based on their hernia type so that primary inguinal hernia surgery could be specifically reviewed.  However this study was limited as results from recurrent inguinal hernias were combined with primary and also reviewed. In addition to this factors, such as including different surgeons and two different surgical procedures affected the accuracy of results.

On the other hand, within Froyliech’s study categorization was based on age and BMI, effective in ensuring that all obese patients had a similar BMI number. Inaccurate results were due to a small sample size, including different surgeons and two different surgical procedures. (Froylich et al., 2016)

The aim is to investigate the impact of obesity on the success rate of inguinal hernia repair, by identifying the amount of recurrences, surgical and postoperative complications.  By eliminating all limitations and factors, the hypothesis can be supported or refuted accurately.

Participants

The hypothesis is tested by reviewing a sample of 2,000 non-obese patients and comparing it to 2,000 obese patients all with primary inguinal hernias, undergoing laparoscopic repair. Patient’s details will be reviewed through HES records to ensure patient’s aged between 30 and 40 with similar BMI numbers and primary inguinal hernias are selected. BMI is effective in considering a person’s body weight and height to determine if they are underweight, obese or healthy. (Wilson, 2017) Anything from 18.5 to 24.9 is considered healthy, but 30 or higher is obese. By ensuring patients with similar BMI numbers are selected it means the range of the scale can be reduced. (webMD, 2016) From this selection patients are then narrowed down further based on their ICD (International classification disease) diagnostic code similarities. Patients that possess any long-term complications or illnesses are eliminated from the sample.

Method

Once 2,000 non-obese and 2,000 obese patients are selected, they undergo laparoscopic inguinal hernia surgery. One surgical procedure is used to prevent the recurrence rate being affected by different repair efficiencies. Every surgical procedure is performed by the same surgeon within a five year timescale. By using the one surgeon it prevents different characteristics having an influence on how it is performed. Eliminating factors that impact the recurrence rate prevents production of inaccurate results. Immediately after the procedure occurs, the surgeon fills out a questionnaire in order to identify any surgical complications that arose. By ensuring the questionnaires are answered straight away, the surgeon’s responses are to the best of their memory, which prevents inaccurate results and analysis. The questionnaire will be based on a scale of 1-5 asking how each procedure went. After the surgical procedure the patient is assessed by nurses to analyse any postoperative complications that may have arose such as, infections, bleeding or organ injuries. This allows interpretation and comparison of any complications that occurred throughout the surgery in non-obese and obese patients. Then another check up on postoperative complications will occur 5 months after the first check up to see whether anymore complications have arose.  

Statistical analysis

Throughout the 5 years after the surgical procedures are performed, patients will be monitored and any inguinal hernia recurrences recorded.  If the patient is diagnosed with another hernia or undergoes further hernia surgery, it is notified and recorded. At the end of the 5 years all the recurrences are calculated and spilt into either obese or non-obese patient categories. An average number and standard deviation of recurrences are calculated for each category to determine how much it differs from the mean value of the group. This allows the recurrence rate in obese and non-obese patients to be compared. A standard deviation and average is calculated for the surgical and postoperative complications in both categories so they can be compared. (Altman & Bland, 2005) Five months later the nurses will perform the assessments again and this is also analysed, averaged and a standard deviation is produced. Overall the recurrence rate, surgical and post-operative complications for the two groups is statically compared using an unpaired T-test allowing the difference in mean to be calculated from the two samples. (Skaik, 2015)

To analyse the relationship between BMI and recurrences, each individual recurrence rate is plotted against their BMI on a scatter graph. A trend line is produced to analyse whether a positive correlation is present. The complications within each individual surgery are plotted against their BMI, to identify whether an increase in BMI increases the amount of complications. A positive correlation trend line clarifies this. (Mukaka, 2012) Another scatter graph is produced to compare the post-operative complications of an individual against their BMI. The same scatter graph is produced to include the results 5 months after. The relationship between BMI and recurrences is calculated through a correlation and regression analysis. Regression analysis identifies the relationship between a dependent and independent variable (Berwick, Cheek, & Ball, 2003)

From these results a relative risk can be calculated and compared against the BMI categories, thus allowing an identification of whether an increase in BMI increases the relative risk of an inguinal hernia recurrence.

Study plan

TASK	START DATE	END DATE	DURATION
A sample of 2,000 obese and 2,000 non-obese patients are selected.	01/02/2017	01/04/2017	2 Months
Surgical procedures are performed using the same surgeon.	01/04/2017	01/04/2022	5 Years
Surgical complications are identified straight after surgery is performed.	01/04/2017	01/04/2022	5 Years
Postoperative complications are identified straight after surgery is performed.	01/04/2017	01/04/2022	5 Years
Postoperative complications are analysed again 5 months later.	01/09/2017	01/09/2022	5 Years
The amount of recurrences are recorded throughout the 5 years after each patients surgery was performed.	01/04/2017	01/04/2027	10 Years
The amount of recurrences are calculated	01/04/2027	01/07/2027	3 Months

Resources required-

Staff	Pay per hour	Hours per week	Yrs	Roles	Equipment required	Cost of equipment	Overall cost
Surgeon Doctors Nurses	NHS funded.	50-60hrs. 59.6hrs. 36hrs.	5 5 5	Hernia surgery. Pre-surgery care & assessments. After surgery care & assessments.	Laparoscope, surgical instruments. X-ray machine, ECG, blood test. Assessment equipment, blood pressure monitor.	NHS funded.	NHS funded.
None	None	0	5	Questionnaire filled out by the surgeon after each patient’s surgery.	2 paged questionnaire.	5p a page.	£400
Data analyst.(payscale, 2017)	£11	16hrs.	2	Gathering the questionnaire results and recording them.	Lenovo think pad W541 mobile workstation.	£  769.92	£9,921.92
Band 5 nurses. (NHS, 2017)	£11.09	2hr per patient	5	Postoperative assessments.	Blood pressure and heart rate monitor, thermometer.	NHS funded.	£88,720
Band 5 nurses. (Royal College Of Nursing, 2016)	£11.09	2hr per patient	5	Postoperative assessments 5 months later.	Blood pressure and heart rate monitor, thermometer.	NHS funded.	£88,720
Data analyst.	£11	8hrs	5	Record any recurrences shown in records.	Lenovo think pad W541 mobile workstation.	Already purchased	£22,080
Statistic analyst.	£13	16hrs	0.4	Finalise the study by calculating overall recurrences, surgical and post-operative complications.	Lenovo think pad W541 mobile workstation.	Already purchased	£23,296
						OVERALL:	£233,137.92