12.2 Case Review: Synthesizing Data, Outliers & Prognosis
Key Takeaways
- Case review follows a repeatable sequence: confirm the etiology, find every barrier to healing (perfusion, infection, pressure, edema, nutrition, glycemia, medications, adherence), set a prognosis, choose treatment and level of care, and set a date to measure progress.
- Outliers deserve a second look: an ankle-brachial index above 1.3 to 1.4 with monophasic waveforms suggests calcified vessels and calls for toe pressures, and a normal white blood cell count or absent fever does not exclude serious diabetic foot infection.
- When several poor prognostic markers occur together, such as severe ischemia, very low albumin from illness, uncontrolled diabetes, and infection, the chance of healing without correcting the dominant barrier is low, and severe ischemia usually has to be addressed first.
- A wound that has not reduced in area by roughly 40% to 50% after 4 weeks of good care should trigger reassessment, and a wound that does not heal despite appropriate care (commonly by about 3 months) or looks atypical should be biopsied.
- Level of care depends on severity: severe infection, sepsis, acute or critical ischemia needing urgent revascularization, and inability to manage safely at home favor admission, while stable wounds with support are managed as outpatients.
12.2 Case Review: Synthesizing Data, Outliers & Prognosis
Core Clinical Principle: Real patients rarely have one problem. Case review means pulling scattered data into one picture, deciding which barrier matters most, spotting results that do not fit, and turning the analysis into a plan with a clear checkpoint.
The CWSP outline lists case review, including analyzing laboratory and imaging results, outliers, prognosis, and synthesis of data, in Patient Management. Many exam items present a scenario with several data points and ask for the most important finding or the best next step.
A Structured Case Review
| Step | Questions to Answer | Typical Data |
|---|---|---|
| 1. Etiology | What caused the wound? Is there more than one cause? | History, location, appearance, pain pattern |
| 2. Perfusion | Is blood flow adequate to heal? | Pulses, ABI, toe pressure or TBI, TcPO2, waveforms, imaging |
| 3. Infection | Is there local infection, spreading infection, or osteomyelitis? | Clinical signs, probe-to-bone, ESR, CRP, WBC, radiographs, MRI, bone biopsy |
| 4. Mechanical forces | Is pressure, shear, or friction being relieved? | Wound location, footwear, support surfaces, adherence |
| 5. Edema | Is swelling slowing healing? | Exam, venous duplex, heart and kidney status |
| 6. Host factors | Are diabetes, nutrition, kidney disease, medications, or smoking impairing repair? | HbA1c, glucose logs, nutrition assessment, medication list |
| 7. Wound bed | Is necrosis, biofilm, or an abnormal edge present? | Tissue types, exudate, edge, response to debridement |
| 8. Person and setting | Can the patient carry out the plan? What are the goals? | Function, cognition, social support, preferences |
| 9. Prognosis and plan | How likely is healing, and what will change first? | Synthesis of the above |
Interpreting Common Data
| Finding | Usual Interpretation | Watch For |
|---|---|---|
| ABI 0.9–1.3 | Normal range | Can be normal with severe distal disease; check waveforms and toe pressures in diabetes and kidney disease |
| ABI above about 1.3–1.4 | Noncompressible, calcified arteries | Obtain toe pressures, TBI, or TcPO2 |
| Toe pressure below 30 mmHg or TcPO2 below 30 mmHg | Severe ischemia with poor healing potential | Urgent vascular referral |
| ESR above about 70 mm/h | Strongly supports osteomyelitis in a diabetic foot ulcer | Also elevated in other inflammatory conditions |
| Positive probe-to-bone test | Supports osteomyelitis, especially when pretest probability is high | A negative test helps rule out osteomyelitis in lower-risk patients |
| Normal radiograph | Does not exclude early osteomyelitis (bone changes take about 2 weeks or more) | Repeat radiographs or obtain MRI |
| Normal WBC, no fever | Does not exclude serious diabetic foot infection | Rely on local and systemic clinical signs |
| Low albumin | Marker of illness severity and inflammation | Not proof of malnutrition |
| HbA1c above target | Poor recent glycemic control | Falsely low with anemia, transfusion, or kidney failure |
Recognizing Outliers
An outlier is a result or course that does not match the working diagnosis. Common examples:
- A "venous" ulcer that fails compression: Recheck arterial status, look for mixed disease, and consider biopsy for malignancy, vasculitis, or pyoderma gangrenosum.
- A diabetic foot ulcer that stalls despite offloading: Check whether the offloading is actually being used, look for osteomyelitis, and remeasure perfusion.
- Pain far out of proportion: Consider calciphylaxis, pyoderma gangrenosum, vasculitis, necrotizing infection, or ischemia.
- Wound enlarging after debridement: Consider pathergy from pyoderma gangrenosum or inadequate perfusion.
- Unusual location or appearance: Rolled edges, exuberant tissue, or an ulcer in a non-pressure area deserves biopsy.
Prognosis
Prognosis combines wound factors (size, duration, depth, grade), perfusion, infection, and host factors. Staging systems help: the SVS WIfI system estimates amputation risk and benefit of revascularization, the University of Texas system adds infection and ischemia to depth, and SINBAD scores site, ischemia, neuropathy, bacterial infection, area, and depth. A 4-week percentage area reduction below roughly 50% for diabetic foot ulcers or 40% for venous leg ulcers signals a low chance of healing by 12 weeks with the current plan.
When several severe findings coexist, the probability of healing without major change is low. For example, a patient with an ABI of 0.4 and TcPO2 of 20 mmHg, uncontrolled diabetes, and very low albumin from chronic illness is very unlikely to heal a foot ulcer without intervention; the ischemia is the dominant barrier because no local therapy can overcome inadequate blood supply.
Choosing the Level of Care and Referrals
| Situation | Usual Level of Care |
|---|---|
| Mild infection, stable perfusion, capable self-care or support | Outpatient wound clinic |
| Needs skilled dressing changes or NPWT and is homebound | Home health |
| Needs daily skilled care or IV antibiotics and cannot manage at home | Skilled nursing facility |
| Severe infection with systemic inflammatory signs, sepsis, rapidly progressive infection, or deep abscess | Hospital admission and urgent surgery |
| Chronic limb-threatening ischemia with tissue loss or acute limb ischemia | Urgent vascular surgery evaluation; admission if acute |
Referrals follow the barriers: vascular surgery for ischemia, infectious diseases for complex or resistant infection, endocrinology for glycemic control, dermatology or rheumatology for atypical or inflammatory ulcers, nephrology for kidney-related wounds, dietitian, physical and occupational therapy, orthotics, social work, and palliative care.
Writing the Plan
- State the etiology and the main barriers in order of importance.
- List actions for each barrier, starting with the dominant one.
- Set a measurable goal (for example, a 50% area reduction in 4 weeks) and a date to review it.
- Document patient goals, education, and who is responsible for each step.
Clinical Traps
Trap 1: Treating the Wound Bed While Ignoring the Limb
Advanced dressings and skin substitutes cannot overcome a toe pressure of 20 mmHg. Fix perfusion first.
Trap 2: Accepting a Reassuring Number That Does Not Fit
A normal-looking ABI of 1.45 in a patient with dialysis-dependent kidney failure is a warning sign of calcified vessels, not proof of good circulation.
A 67-year-old man with type 2 diabetes has a 3-month-old plantar forefoot ulcer. Findings: HbA1c 10%, BMI 37 kg/m², albumin 1.5 g/dL with high CRP, ABI 0.40, TcPO2 20 mmHg on the dorsal foot, and no signs of infection. He has used a knee-high offloading walker consistently. Which barrier is most important to address first, and why?
A 72-year-old woman on hemodialysis has a nonhealing heel ulcer. Her ABI is 1.48 bilaterally, but Doppler waveforms at the ankle are monophasic. What is the best interpretation and next step?
A 59-year-old man with diabetes has a plantar foot ulcer with 4 cm of surrounding erythema, purulent drainage, a temperature of 38.9°C, heart rate of 118 beats per minute, respiratory rate of 24 breaths per minute, and a WBC count of 16,500/µL. What is the most appropriate level of care?