PHQ-9 Total Calculator

PHQ-9nine independently coded0–3frequency items; this arithmetic is not a diagnosis or an assessment of immediate safety. Sum only independently assessed codes for the declared instrument/version; exact maxima [3, 3, 3, 3, 3, 3, 3, 3, 3] and minima [0, 0, 0, 0, 0, 0, 0, 0, 0]. Unknown items preserve possible total bounds without imputation. No questionnaire reproduction, clinical item assignment, norm, diagnosis, treatment or outcome prediction.

Description

PHQ-9 totals summarize nine independently coded symptom items.

PHQ-9 totals summarize nine independently coded symptom items.^[1]

Missing evidence produces a possible range rather than a completed screen or diagnosis.

When to use PHQ-9 Total Calculator

Use this tool to calculate or review the supplied observations under the stated rules. Establish the assessment or recording protocol, units, instrument version and independently applicable reference or calibration.

How to use PHQ-9 Total Calculator and understand its results

Establish the assessment or recording protocol, units, instrument version and independently applicable reference or calibration.
Enter independentlyCodedItemScores, itemKnownFlags, using the field meanings and rules below, then run the tool.
Read result.knownItemSum, result.minimumPossibleTotal, result.maximumPossibleTotal, result.unknownItemIndices. Use the units and sign conventions below. Review unresolved records and any possible bounds separately from known results.
Correct any reported input issue and run again. Before using a successful result, check the stated units, signs, reference scope and observation coverage.

Input field	Meaning	Value type	Requirement
independentlyCodedItemScores	Independently coded item scores	list of number	Required
itemKnownFlags	Item known flags; binary 1 means the matched observation is known, 0 means unknown	list of number	Required

Enter exactly 9 independently coded scores and matched binary known flags. The per-position inclusive minima are [0,0,0,0,0,0,0,0,0] and maxima are [3,3,3,3,3,3,3,3,3]. Scores must be multiples of 1, checked within a 1e-10 tolerance in score/step. Every score, including an unknown placeholder, must obey the bounds. Sum known scores; add unknown minima and maxima for possible total bounds. Unknown item indices are zero-based. Reverse coding, administration, item order and applicability are externally established; the tool does not supply questions, perform an assessment or select clinical cutoffs.

Zero-based column	Criterion
0	Adopted component 0: minimum 0, maximum 3; independently apply the instrument's item order and key
1	Adopted component 1: minimum 0, maximum 3; independently apply the instrument's item order and key
2	Adopted component 2: minimum 0, maximum 3; independently apply the instrument's item order and key
3	Adopted component 3: minimum 0, maximum 3; independently apply the instrument's item order and key
4	Adopted component 4: minimum 0, maximum 3; independently apply the instrument's item order and key
5	Adopted component 5: minimum 0, maximum 3; independently apply the instrument's item order and key
6	Adopted component 6: minimum 0, maximum 3; independently apply the instrument's item order and key
7	Adopted component 7: minimum 0, maximum 3; independently apply the instrument's item order and key
8	Adopted component 8: minimum 0, maximum 3; independently apply the instrument's item order and key

knownSum=Σ(score_i×known_i); possibleMin=knownSum+Σ_unknown(min_i); possibleMax=knownSum+Σ_unknown(max_i)

Use the matching field units and the exact boundary, ordering and reference rules above.

Output field	Meaning	Value type
result	Structured result; its nested fields below contain the actual calculation or selected reference	object
result.knownItemSum	Sum of independently coded scores whose known flag equals 1; partial if any item is unknown	number
result.minimumPossibleTotal	Known contribution plus every unknown component's permitted minimum	number
result.maximumPossibleTotal	Known contribution plus every unknown component's permitted maximum	number
result.unknownItemIndices	Zero-based positions of items marked unknown	list

json

{
  "input": {
    "independentlyCodedItemScores": [
      1,
      1,
      1,
      1,
      1,
      1,
      1,
      1,
      1
    ],
    "itemKnownFlags": [
      1,
      1,
      1,
      1,
      1,
      1,
      1,
      1,
      1
    ]
  },
  "output": {
    "result": {
      "knownItemSum": 9,
      "minimumPossibleTotal": 9,
      "maximumPossibleTotal": 9,
      "unknownItemIndices": []
    }
  }
}

Limitations and assumptions

Actual acquisition, assessment protocol, instrument version and calibration determine applicability. The tool does not examine a person, classify images, administer a questionnaire or choose diagnostic cutoffs.

Missing required fields, unknown fields, wrong types and violated rules return input issues. Numeric values and outputs must be finite. Lists and matrices must be dense, without missing cells. Numeric lists allow at most 10000 entries; ordinary string lists allow at most 128 strings of 128 UTF-16 units each; numeric matrices allow at most 128 rows and 128 columns, subject to narrower requirements above. Extremely large composite outputs are rejected.

Alternative or Complementary methods

For a related step, use Yale-Brown Obsessive Compulsive Scale Calculator: The Yale–Brown obsessive-compulsive scale summarizes independently coded symptom-severity items under an adopted version. For a complementary comparison, use MADRS Total Calculator: MADRS totals summarize independently coded depression-severity items under an adopted version.

References

PHQ-9 Total Calculator — tool.io

Similar or alternative tools

Yale-Brown Obsessive Compulsive Scale Calculator
The Yale–Brown obsessive-compulsive scale summarizes independently coded symptom-severity items under an adopted version.
MADRS Total Calculator
MADRS totals summarize independently coded depression-severity items under an adopted version.