This retrospective cohort study reviewed daily admissions to our center of patients with an intertrochanteric or femoral fracture from 1 January 2009 through 31 January 2020. A trained research associate collected patient’s data through a review of hospital medical records. Baseline characteristics of patients were obtained from reviews of medical charts.

The inclusion criteria were age 18 years or older on admission and having undergone a primary inpatient surgical hip fracture procedure. The exclusion criteria were patients without a hip fracture or with no procedure codes for hip fracture surgery, patients with a previous hip fracture, patients with a length of hospital stay of more than 30 days, patients who used other strong opioids and other routes of morphine consumption, and patients who underwent a local nerve block during the hip operation. The patients were divided into two groups: patients who received intravenous morphine (the IV group) and patients who received the other analgesics group. Information was obtained on all analgesic drugs administered for each patient, including oral and injection medications as well as the use of transdermal patches.

We determined the total IV morphine each patient consumed using medical records and chart reviews, both certified by a physician and a nurse. According to hospital policy, the usage of IV morphine is also monitored by requiring that any unused IV drugs be returned to the hospital and that the amounts returned be recorded. The quantity of IV morphine used was categorized into that used before surgery, post-operation, and recovery prior to rehabilitation. We also recorded the frequency of use separately to help confirm the total consumption and to calculate the average IV morphine dosage. Notes on anesthesia use and patient medical records provided patient body weight information. We calculated the per kilogram dose by dividing the total amount used by the patient's body weight. To calculate postoperative morphine use, the quantity of postoperative IV morphine used was divided by body mass since the surgery was conducted after the first rehabilitation period.

All other analgesics used for each patient were tracked using the hospital's analgesic drug lists for four categories of analgesic drugs: acetaminophen, non-selective NSAIDs, selective NSAIDs, and weak opioids. Each category of drug was then separated into oral drugs and IV drugs. The total consumption, total cost, and cost per unit of each of the analgesic drugs was recorded. The per unit cost by weight of each drug was used to calculate the total cost of drugs used with each patient.

Three routes are available for analgesic drug administration: oral, injection, and patch form. The oral route was the standard used for pain control while injection was used in cases of 99%. As the patch was used with only a small minority of patients, data on patch delivery was recorded but was not used in the comparison of the two study groups. Analgesic drug usage and cost in the IV and other analgesics groups were also collected and compared.

We examined the relationship between the level of pain in the IV and other analgesics groups as well as in-hospital outcomes, including total hospital cost, analgesic drug cost, length of stay, postoperative complications, time to rehabilitation, pain score before and after rehabilitation, delay in ambulation, analgesic complications, and functional outcomes. Based on the data available in hospital records, patients' level of pain was calculated as a numeric score on a scale of 1 to 10, where NS 1 = no pain and NS 10 = very severe pain. Pain scores were determined immediately after a patient was transferred to the ward following surgery then every 4 h until entry into the the rehabilitation program. Patients with moderate (NS 5-7) to severe pain (NS > 7) were identified and their analgesic drug use information was recorded. Physicians independently reviewed each patient's complications which had been recorded at the initial visit plus the dosages of antiemetic drugs following the International Statistical Classification of Diseases and Related Health Problems (ICD10).

Potential adverse effects of analgesic drugs, identified from PubMed and Scopus, include problems involving the respiratory system, gastrointestinal system, central nervous system and genitourinary system, as well as other adverse effects such as bradycardia, rash, itching, and falls from bed. Each possible adverse effect was matched with ICD-10 and the patient's history in the medical record following the hip fracture event. All the adverse effects are collected before using therapeutic drugs such as PPIs, antiemetics, and antibiotics drugs.

Analgesic drugs used for each patient, including name, type, total cost, unit price, and total consumption, were obtained from the hospital records database. The number of drugs and the total cost of the drugs were recorded. The unit price of each analgesic drug was recorded at the time of use as some prices change over time. Trends in use of individual drugs were plotted to identify changes over time.

Patient analgesic use was divided into two groups: analgesics prescribed as needed and those prescribed preemptively using a pain score cut point of 3. Selected patient characteristics were used in the analysis for weighted adjustment, including actual age, age > 70 years, gender, BMI, body weight, height, type of fracture, type of operation, operation time, and type of anesthesia. Hospital costs, quantity, and cost of analgesic drugs were calculated and categorized by group. The heterogeneity of unweighted and weighted groups were defined by absolute standardized difference. Differences in continuous variables between the 2 groups were assessed using weight median regression; differences between categorical variables were determined using weight risk difference regression. Associations were considered statistically significant if p < 0.05. Statistical analysis was performed using STATA version 16 (StataCorp, College Station, TX, USA) and Microsoft Excel (Microsoft 365, Microsoft, Seattle, WA, USA).