Study area

The study was conducted at Debre Tabor comprehensive specialized Hospital and Felege Hiwot comprehensive specialized Hospital in the Amhara regional state of Northwest Ethiopia. All of these Hospitals have operation rooms that give services on elective and emergency bases. Approximately 15,000–20,000 patients undergo surgery in these hospitals per year. These referral hospitals were providing services for a population of around 30 million populations. These hospitals provide services like diagnosis, and treatment, for different procedures.

Study design and period

A multicenter prospective observational cohort study was conducted from June 01 to August 30, 2022.

Source population

All adult patients who were scheduled for major elective orthopedic surgery who underwent surgery in Amhara Regional State Governmental Hospitals of Ethiopia.

Study population

Selected patients who underwent major elective orthopedic surgery in selected Amhara regional state governmental Hospitals of Ethiopia during study period.

Inclusion and exclusion criteria

Study participants who were included in this study selected all patients 18 years and above who underwent major orthopaedics surgery were included. No preoperative haemoglobin record, Patient refusal, day-case surgery, and Patient on treatments of anaemia would be excluded from the study.

Dependent variable

Preoperative anemia of major elective orthopedic surgery.

Independent variables

Socio-economic and demographic variables (age, sex, BMI, ASA status, educational status, occupation, residence), comorbidity (peptic ulceration, myocardial infarction, hypertension, HIV, malaria, diabetes mellitus, malignancy, asthma, and renal disease), medications (chronic use of non-steroidal anti-inflammatory drugs (NSAID), antiretroviral therapy, and chemotherapy drugs.

Sample size and sampling technique

At the national level, there is no documented information on the prevalence of preoperative anemia in orthopedics surgery and its associated factors. Using the finite population correction formula, the sample size was estimated by assuming a 0.5 prevalence of preoperative anemia in orthopedics surgery and a 5% margin of error at a 95% confidence interval using the following calculations.

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Where; n = sample size Z = confidence interval (1.96) P = estimated prevalence (0.5) d = margin of sampling error to be tolerated (0.05) & ἀ= 5%.

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The total number of adult elective orthopedics surgery performed in the hospital annually was below 10,000 and we found only average of 92 elective orthopedics surgery procedures done per a month by reviewing the operation registry and we were taken three consecutive months with similar to our data collection month. So, we were taken the three months totally we were taken 276. So we decided to apply reduction formula to obtain an achievable sample size.

nf = n/ (1 + n/N), N = 276…. correction formula for population less than 10,000.

So, nf = 384/ (1 + 384/276) = 160.6 Correction formula for population less than 10,000. Major elective orthopedic surgery patients.

We added 10% of nf for the non-response rate; (i.e., 160.6 + 16 = 176.6); As a result, a total of 177 adult major elective orthopedic surgery patients were included in this research.

Finally a systematic sampling technique was used to obtain the required sample size. The second case was chosen by lottery, and every kth patient was chosen for the study period.

$$}\,}\,}\,}\,}\,}\,}\,}\,}\,}\,}$$

N = population the last three months 276, sample interval = 276/177 = 1.56 ≈ 2.

Therefore, the sampling interval was two and the first study participant was selected using the lottery method from the daily surgery list of major elective orthopedics scheduled case.

Data collection instruments and procedures

Data was collected by using an English version structure questionnaire taken from studies and translated to the Amharic language. The data collection procedure includes chart review and patient interview using a structured questionnaire. Data was collected from patients or caregivers by using a structured checklist questionnaire. Hemoglobin measurements were obtained from the patient’s medical records by reviewing charts. The data was collected by three trained BSc anesthetists after taking training on how to collect the questionnaire.

Data quality assurance

Pretest was done to ensure the quality of data in 18 (10%) of the sample size) patients from other hospitals who were not included in the main study. Then, the necessary corrections were done accordingly to the questionnaire for the main study. Three days of training were given to the data collector and supervisor on the aim and objective of the study, the supervision, and the data collection process. The collected data were checked for completeness, accuracy, and clarity. Incomplete data were discarded and counted as non-response. Daily supervision and feedback were given by the principal investigator and supervisor during the data collection period.

Data entry, analysis, and interpretation

The collected data were coded, entered into the Epi-data software (version 7) for cleaning errors, and analyzed by SPSS version 26. Descriptive statistical analyses were performed and presented with frequency, percentage, median, mean, and standard deviation. Hosmer and Lemeshow test was used to assess the goodness of fit. Variables with a p-value of less than < 0.2 in the Bivariable logistic analysis were fitted into a multivariable logistic regression analysis. The associations between the independent variables and dependent variables were determined at a 95% confidence interval with the chi-squared test, bivariate, and multivariate binary logistic regression, and presented in crude and adjusted odds ratio. In multivariable logistic regression analysis, variables with a p-value < 0.05 were considered statistically significant.

Ethical consideration

Ethical clearance was received from the ethical reviewing committee and permission to conduct this research was obtained from the research and community service coordinator office of Debre Tabor University with the reference number CHS/1799/2014. Written informed consent was presented and obtained from each study participant according to the principles of the Helsinki Declaration. The Declaration of Helsinki was considered and principles and recommendations have been used.

Operational definition Anemia

is reduction of a hemoglobin (Hb) level below 12 g/dL (hematocrit < 36%) for nonpregnant women and 13.0 g/dL(hematocrit < 39%) for men [17].

Mild anemia

is hemoglobin (Hb) between 11 and 11.9 g/dL in non-pregnant women. Moderate: Hemoglobin 8.0-10.9 g/dL. Severe: Hemoglobin less than 8.0 g/dL [18].

Adult patient

- age of patient 18 years and above years for both genders.

Preoperative Hb

The most recent Hb assessed within 28 days before surgery was considered [19].

Orthopedic injury

is defined as an injury affecting the musculoskeletal system, which includes injuries to bones, joints, ligaments, tendons, muscles, and nerves.

Multiple sites fracture

defined as any types of fractures at two or more sites of the musculo-skeletal system.

Orthopedics surgery

- is a type of surgery in which a medical professional, such as an orthopedist or orthopedic surgeon, performs surgery on the bones, joints, and ligaments of the human body to correct disorders [20].